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.

decnet/orchestrator/emailgen/__init__.py

@@ -1,33 +1,20 @@
-"""Emailgen — second orchestrator worker.
+"""Emailgen — email-specific delivery, scheduling, and threading.
 
-Generates fake corporate emails (multi-language, threaded, persona-driven)
-and drops them into mail-decky maildirs so attackers landing on
-IMAP/POP3 honeypots find believable mailboxes instead of empty inboxes.
+After stage 5 of the realism migration, ``emailgen`` is no longer a
+separate worker / systemd unit / CLI subcommand.  It exposes:
 
-The module is intentionally a sibling of :mod:`decnet.orchestrator` (not
-a flag on it) — separate worker, separate CLI command
-(``decnet emailgen``), separate systemd-supervised lifecycle. Shares the
-heartbeat / control-listener scaffolding via :mod:`decnet.bus.publish`.
+* :mod:`decnet.orchestrator.emailgen.scheduler` — the
+  ``EmailAction`` shape and the ``pick(repo)`` policy that decides
+  which mail decky / sender / recipient / thread an email belongs to.
+* :mod:`decnet.orchestrator.emailgen.threads` — RFC 2822 thread chain
+  helpers (Message-ID generation, Re: / In-Reply-To bookkeeping).
+* :mod:`decnet.orchestrator.emailgen.events` — DB-row + bus-topic
+  builders for email events.
 
-Lazy worker re-export: :func:`emailgen_worker` is loaded on first
-attribute access so that submodules can import package-level names
-(``decnet.orchestrator.emailgen.events``) without triggering an eager
-load of the worker — and through it, the email driver, which imports
-back into this package.  Without lazy loading the package + driver +
-worker form a cycle.
+The orchestrator's main worker (:mod:`decnet.orchestrator.worker`)
+calls into these modules per tick.  LLM glue, persona schema, prompt
+builder, and the global persona pool moved to :mod:`decnet.realism`
+in stage 2 of the migration; this package keeps only the
+email-specific delivery surface.
 """
 from __future__ import annotations
-
-from typing import TYPE_CHECKING, Any
-
-if TYPE_CHECKING:  # pragma: no cover - typing only
-    from decnet.orchestrator.emailgen.worker import emailgen_worker  # noqa: F401
-
-__all__ = ["emailgen_worker"]
-
-
-def __getattr__(name: str) -> Any:
-    if name == "emailgen_worker":
-        from decnet.orchestrator.emailgen.worker import emailgen_worker as _w
-        return _w
-    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")

decnet/orchestrator/emailgen/worker.py

@@ -1,131 +0,0 @@
-"""Emailgen main loop.
-
-Mirrors :mod:`decnet.orchestrator.worker` shape: same heartbeat, same
-control listener, same fire-and-forget bus publish, same prune knob.
-A wedged ollama call stalls only this worker, never the SSH-flavoured
-orchestrator running alongside.
-"""
-from __future__ import annotations
-
-import asyncio
-import contextlib
-
-from decnet.bus.factory import get_bus
-from decnet.bus.publish import (
-    publish_safely,
-    run_control_listener,
-    run_health_heartbeat,
-)
-from decnet.logging import get_logger
-from decnet.orchestrator.drivers.email import EmailDriver
-from decnet.orchestrator.emailgen import events, scheduler
-from decnet.web.db.repository import BaseRepository
-
-logger = get_logger("orchestrator.emailgen")
-
-# Periodic-prune knobs — same shape as orchestrator/worker.py.
-_PRUNE_EVERY_TICKS = 100
-_PRUNE_PER_DECKY_CAP = 5000
-
-
-async def emailgen_worker(
-    repo: BaseRepository,
-    *,
-    interval: int = 300,
-    model: str | None = None,
-) -> None:
-    """Periodically generate one fake email into a running mail decky.
-
-    Default interval is 5 minutes — emails are expensive (LLM round
-    trip) and don't need to fire every minute to look natural.  Honors
-    ``system.emailgen.control`` for graceful shutdown.
-    """
-    logger.info("emailgen worker started interval=%ds model=%s", interval, model)
-
-    bus = None
-    try:
-        bus = get_bus(client_name="emailgen")
-        await bus.connect()
-    except Exception as exc:  # noqa: BLE001
-        logger.warning(
-            "emailgen: bus unavailable, continuing without publish: %s", exc
-        )
-        bus = None
-
-    driver = EmailDriver(model=model) if model else EmailDriver()
-    shutdown = asyncio.Event()
-    heartbeat_task = asyncio.create_task(run_health_heartbeat(bus, "emailgen"))
-    control_task = asyncio.create_task(
-        run_control_listener(bus, "emailgen", shutdown),
-    )
-    tick_n = 0
-    try:
-        while not shutdown.is_set():
-            try:
-                await asyncio.wait_for(shutdown.wait(), timeout=interval)
-            except asyncio.TimeoutError:
-                pass  # normal tick
-            if shutdown.is_set():
-                break
-            try:
-                await _one_tick(repo, driver, bus)
-            except Exception as exc:  # noqa: BLE001
-                logger.error("emailgen tick failed: %s", exc)
-            tick_n += 1
-            if tick_n % _PRUNE_EVERY_TICKS == 0:
-                try:
-                    deleted = await repo.prune_orchestrator_emails(
-                        per_decky_cap=_PRUNE_PER_DECKY_CAP,
-                    )
-                    if deleted:
-                        logger.info(
-                            "emailgen prune deleted=%d cap=%d",
-                            deleted, _PRUNE_PER_DECKY_CAP,
-                        )
-                except Exception as exc:  # noqa: BLE001
-                    logger.error("emailgen prune failed: %s", exc)
-    finally:
-        for t in (heartbeat_task, control_task):
-            t.cancel()
-            with contextlib.suppress(Exception, asyncio.CancelledError):
-                await t
-        if bus is not None:
-            with contextlib.suppress(Exception):
-                await bus.close()
-
-
-async def _one_tick(repo: BaseRepository, driver: EmailDriver, bus) -> None:
-    action = await scheduler.pick(repo)
-    if action is None:
-        logger.debug("emailgen: no actionable mail decky / personas this tick")
-        return
-
-    result = await driver.run(action)
-    row = events.to_row(action, result)
-    await repo.record_orchestrator_email(row)
-
-    if bus is not None:
-        topic = events.topic_for(action)
-        # Mirror the orchestrator-event SSE-friendly payload shape: ts
-        # as iso8601, payload as already-serialised dict.
-        bus_payload = {
-            "kind": "email",
-            "mail_decky_uuid": row["mail_decky_uuid"],
-            "thread_id": row["thread_id"],
-            "message_id": row["message_id"],
-            "in_reply_to": row["in_reply_to"],
-            "sender_email": row["sender_email"],
-            "recipient_email": row["recipient_email"],
-            "subject": row["subject"],
-            "language": row["language"],
-            "success": row["success"],
-            "ts": row["ts"].isoformat(),
-        }
-        await publish_safely(
-            bus, topic, bus_payload, event_type=events.event_type_for(action),
-        )
-
-    logger.info(
-        "emailgen tick mail_decky=%s thread=%s success=%s reply=%s",
-        row["mail_decky_uuid"], row["thread_id"], row["success"], action.is_reply,
-    )