refactor(orchestrator): collapse decnet-emailgen.service into orchestrator

Stage 5 of the realism migration. Email generation is no longer a
separate worker / systemd unit / CLI subcommand — the orchestrator's
single tick loop covers SSH traffic, file plants, and email drops.
Going from 21 services to 20.

Worker:
- _one_tick rolls between traffic / file / email (45/45/10 weights).
  The 10% email weight at a 60s orchestrator interval produces ~one
  email per 10 minutes, close to the pre-collapse 5-minute cadence.
- get_driver_for(action) (stage 4) handles SSH vs Email dispatch.
- Quiet branches fall through so a (decky-set, persona-pool,
  mail-decky) shape that silences one branch doesn't waste the tick.
- Periodic prune covers both orchestrator_events and
  orchestrator_emails tables.

Deletions:
- deploy/decnet-emailgen.service.j2
- decnet/orchestrator/emailgen/worker.py
- decnet/cli/emailgen.py
- tests/orchestrator/emailgen/test_worker_integration.py

Renames (history-preserving):
- decnet/web/router/emailgen/ -> decnet/web/router/realism/
- tests/api/emailgen/        -> tests/api/realism/
- tests/cli/test_emailgen_*  -> tests/cli/test_realism_*

Public surface changes (clean break, pre-v1):
- API URL /api/v1/emailgen/personas -> /api/v1/realism/personas
- CLI `decnet emailgen import-personas` -> `decnet realism
  import-personas`. `decnet emailgen run` is gone — the orchestrator
  covers it.
- gating.py: emailgen master-only group replaced by realism.
- decnet-orchestrator.service.j2: DECNET_REALISM_* env block added.
- decnet.target: decnet-emailgen.service entry removed.
- frontend: PersonaGeneration.tsx fetches /realism/personas.

tests/cli/test_realism_gating.py

@@ -1,9 +1,9 @@
-"""``decnet emailgen`` is master-only.
+"""``decnet realism`` is master-only.
 
 Two layers per CLAUDE.md:
 
 * registration-time hide via :data:`MASTER_ONLY_GROUPS` so agents don't
-  see ``decnet emailgen`` in ``--help`` at all,
+  see ``decnet realism`` in ``--help`` at all,
 * body-guard ``_require_master_mode()`` so a direct callable import (e.g.
   from a third-party tool) still bails on agent hosts.
 """
@@ -17,7 +17,6 @@ import sys
 from pathlib import Path
 
 import pytest
-from typer.testing import CliRunner
 
 
 REPO = pathlib.Path(__file__).resolve().parent.parent.parent
@@ -32,7 +31,7 @@ def _clean_env(**overrides: str) -> dict[str, str]:
     return base
 
 
-def test_emailgen_visible_in_master_mode():
+def test_realism_visible_in_master_mode():
     result = subprocess.run(
         [str(DECNET_BIN), "--help"],
         env=_clean_env(DECNET_MODE="master"),
@@ -40,10 +39,10 @@ def test_emailgen_visible_in_master_mode():
         capture_output=True, text=True, timeout=20,
     )
     assert result.returncode == 0
-    assert "emailgen" in result.stdout
+    assert "realism" in result.stdout
 
 
-def test_emailgen_hidden_in_agent_mode():
+def test_realism_hidden_in_agent_mode():
     result = subprocess.run(
         [str(DECNET_BIN), "--help"],
         env=_clean_env(DECNET_MODE="agent", DECNET_DISALLOW_MASTER="true"),
@@ -51,25 +50,12 @@ def test_emailgen_hidden_in_agent_mode():
         capture_output=True, text=True, timeout=20,
     )
     assert result.returncode == 0
-    # The sub-app's help string must be gone too — bare "emailgen" can
+    # The sub-app's help string must be gone too — bare "realism" can
     # appear in other command descriptions.
-    assert "Drip persona-driven fake corporate email" not in result.stdout
+    assert "realism content engine" not in result.stdout
 
 
-def test_emailgen_subprocess_run_rejects_in_agent_mode():
-    """Subprocess-level: a fresh Python invocation of `decnet emailgen
-    run` under DECNET_MODE=agent must exit non-zero (gate hides the
-    sub-app, so the command is unknown to Typer)."""
-    result = subprocess.run(
-        [str(DECNET_BIN), "emailgen", "run"],
-        env=_clean_env(DECNET_MODE="agent", DECNET_DISALLOW_MASTER="true"),
-        cwd=str(REPO),
-        capture_output=True, text=True, timeout=20,
-    )
-    assert result.returncode != 0
-
-
-def test_emailgen_subprocess_import_personas_rejects_in_agent_mode(tmp_path):
+def test_realism_subprocess_import_personas_rejects_in_agent_mode(tmp_path):
     src = tmp_path / "personas.json"
     src.write_text(json.dumps([{
         "name": "X", "email": "x@y.com", "role": "X", "tone": "formal",
@@ -79,7 +65,7 @@ def test_emailgen_subprocess_import_personas_rejects_in_agent_mode(tmp_path):
         "mannerisms": [],
     }]))
     result = subprocess.run(
-        [str(DECNET_BIN), "emailgen", "import-personas", str(src)],
+        [str(DECNET_BIN), "realism", "import-personas", str(src)],
         env=_clean_env(DECNET_MODE="agent", DECNET_DISALLOW_MASTER="true"),
         cwd=str(REPO),
         capture_output=True, text=True, timeout=20,
@@ -89,7 +75,7 @@ def test_emailgen_subprocess_import_personas_rejects_in_agent_mode(tmp_path):
 
 def test_require_master_mode_body_guard_fires_directly(monkeypatch):
     """Defence-in-depth: even bypassing Typer registration, the body-level
-    ``_require_master_mode('emailgen ...')`` raises ``typer.Exit``.  Same
+    ``_require_master_mode('realism ...')`` raises ``typer.Exit``.  Same
     mechanism is verified for `api`/`deploy` in test_mode_gating.py."""
     import typer
 
@@ -99,13 +85,13 @@ def test_require_master_mode_body_guard_fires_directly(monkeypatch):
     monkeypatch.setenv("DECNET_DISALLOW_MASTER", "true")
 
     with pytest.raises(typer.Exit):
-        _require_master_mode("emailgen run")
+        _require_master_mode("realism import-personas")
 
 
 def test_master_mode_falls_through_body_guard(monkeypatch):
     """In master mode the guard is a no-op (raises nothing)."""
-    from decnet.cli.gating import _require_master_mode
+    from decnet.cli.gating import _require_master_mode  # noqa: F401
 
     monkeypatch.setenv("DECNET_MODE", "master")
     # Should simply return.
-    _require_master_mode("emailgen run")
+    _require_master_mode("realism import-personas")

tests/cli/test_realism_import_personas.py

@@ -1,4 +1,4 @@
-"""``decnet emailgen import-personas`` CLI command."""
+"""``decnet realism import-personas`` CLI command."""
 from __future__ import annotations
 
 import json
@@ -42,7 +42,7 @@ def test_import_personas_writes_canonical_file(tmp_path, monkeypatch):
     monkeypatch.setenv("DECNET_REALISM_PERSONAS", str(dest))
 
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code == 0, result.stdout
     assert dest.exists()
@@ -59,7 +59,7 @@ def test_import_personas_explicit_output_overrides_env(tmp_path, monkeypatch):
 
     result = CliRunner().invoke(
         app,
-        ["emailgen", "import-personas", str(src), "--output", str(explicit)],
+        ["realism", "import-personas", str(src), "--output", str(explicit)],
     )
     assert result.exit_code == 0, result.stdout
     assert explicit.exists()
@@ -70,7 +70,7 @@ def test_import_personas_rejects_invalid_json(tmp_path):
     src = tmp_path / "src.json"
     src.write_text("{not valid")
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code != 0
     assert "Invalid JSON" in result.stdout
@@ -81,7 +81,7 @@ def test_import_personas_rejects_non_list(tmp_path, monkeypatch):
     src.write_text(json.dumps({"not": "a list"}))
     monkeypatch.setenv("DECNET_REALISM_PERSONAS", str(tmp_path / "out.json"))
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code != 0
     assert "list" in result.stdout.lower()
@@ -94,7 +94,7 @@ def test_import_personas_rejects_all_invalid_entries(tmp_path, monkeypatch):
     ]))
     monkeypatch.setenv("DECNET_REALISM_PERSONAS", str(tmp_path / "out.json"))
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code != 0
     assert "No valid personas" in result.stdout
@@ -106,7 +106,7 @@ def test_import_personas_warns_on_single_persona(tmp_path, monkeypatch):
     dest = tmp_path / "out.json"
     monkeypatch.setenv("DECNET_REALISM_PERSONAS", str(dest))
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code == 0, result.stdout
     assert "Warning" in result.stdout
@@ -120,7 +120,7 @@ def test_imported_personas_load_via_global_pool(tmp_path, monkeypatch):
     monkeypatch.setenv("DECNET_REALISM_PERSONAS", str(dest))
 
     result = CliRunner().invoke(
-        app, ["emailgen", "import-personas", str(src)]
+        app, ["realism", "import-personas", str(src)]
     )
     assert result.exit_code == 0, result.stdout