feat(emailgen): Ollama-driven fake email worker for IMAP/POP3 deckies

Second orchestrator worker (decnet emailgen) that drips persona-driven,
threaded, multi-language fake emails into running mail deckies.  Personas
live on Topology.email_personas; topology-wide language_default falls
through to any persona that doesn't pin its own.  Em-dashes are
suppressed at the prompt layer by default and only lifted for personas
explicitly marked uses_llms_heavily — em-dashes are an LLM tell and a
flat corpus of em-dashed mail is a giveaway.

EML delivery writes into /var/spool/decnet-emails/<thread>/<msg>.eml on
the mail decky via docker exec; wiring the IMAP/POP3 templates to read
from that spool (replacing the hardcoded _BAIT_EMAILS) is the next step.

tests/orchestrator/emailgen/test_repo.py

@@ -0,0 +1,129 @@
+"""record / list / count / prune orchestrator_emails on a real SQLite repo."""
+from __future__ import annotations
+
+import json
+from datetime import datetime, timedelta, timezone
+
+import pytest
+import pytest_asyncio
+
+from decnet.web.db.sqlite.repository import SQLiteRepository
+
+
+@pytest_asyncio.fixture
+async def repo(tmp_path):
+    r = SQLiteRepository(db_path=str(tmp_path / "decnet.db"))
+    await r.initialize()
+    yield r
+    await r.engine.dispose()
+
+
+def _row(
+    mail="d1",
+    thread="thr1",
+    msg="<m1@x>",
+    sender="john@corp.com",
+    recipient="sarah@corp.com",
+    subject="Q3 budget",
+    success=True,
+    in_reply_to=None,
+    ts=None,
+):
+    return {
+        "ts": ts or datetime.now(timezone.utc),
+        "mail_decky_uuid": mail,
+        "thread_id": thread,
+        "message_id": msg,
+        "in_reply_to": in_reply_to,
+        "sender_email": sender,
+        "recipient_email": recipient,
+        "subject": subject,
+        "language": "en",
+        "eml_path": f"/var/spool/decnet-emails/{thread}/{msg}.eml",
+        "success": success,
+        "payload": {"model": "llama3.1"},
+    }
+
+
+@pytest.mark.asyncio
+async def test_record_returns_uuid_and_serialises_payload(repo):
+    uuid = await repo.record_orchestrator_email(_row())
+    assert isinstance(uuid, str) and len(uuid) == 36
+    rows = await repo.list_orchestrator_emails()
+    assert len(rows) == 1
+    # payload is stored as JSON text, list endpoint hands it back as the
+    # raw column value — we just verify it round-trips intact.
+    assert json.loads(rows[0]["payload"])["model"] == "llama3.1"
+
+
+@pytest.mark.asyncio
+async def test_list_filters_by_thread_and_mail_decky(repo):
+    await repo.record_orchestrator_email(_row(thread="t1", msg="<a@x>"))
+    await repo.record_orchestrator_email(_row(thread="t2", msg="<b@x>"))
+    await repo.record_orchestrator_email(_row(mail="d2", msg="<c@x>"))
+
+    by_thread = await repo.list_orchestrator_emails(thread_id="t1")
+    assert {r["message_id"] for r in by_thread} == {"<a@x>"}
+
+    by_mail = await repo.list_orchestrator_emails(mail_decky_uuid="d1")
+    assert len(by_mail) == 2
+
+    everything = await repo.list_orchestrator_emails()
+    assert len(everything) == 3
+
+
+@pytest.mark.asyncio
+async def test_count_orchestrator_emails(repo):
+    for i in range(3):
+        await repo.record_orchestrator_email(_row(msg=f"<m{i}@x>"))
+    assert await repo.count_orchestrator_emails() == 3
+    assert await repo.count_orchestrator_emails(mail_decky_uuid="d1") == 3
+    assert await repo.count_orchestrator_emails(mail_decky_uuid="other") == 0
+
+
+@pytest.mark.asyncio
+async def test_thread_lookup_only_returns_pair_threads(repo):
+    await repo.record_orchestrator_email(
+        _row(sender="john@corp.com", recipient="sarah@corp.com", msg="<a@x>")
+    )
+    # Reverse direction (Sarah → John) should still match the same pair.
+    await repo.record_orchestrator_email(
+        _row(sender="sarah@corp.com", recipient="john@corp.com", msg="<b@x>")
+    )
+    # Unrelated pair must not match.
+    await repo.record_orchestrator_email(
+        _row(sender="mike@corp.com", recipient="sarah@corp.com", msg="<c@x>")
+    )
+    threads = await repo.list_orchestrator_email_threads(
+        "d1", "john@corp.com", "sarah@corp.com",
+    )
+    assert {t["message_id"] for t in threads} == {"<a@x>", "<b@x>"}
+
+
+@pytest.mark.asyncio
+async def test_thread_lookup_excludes_failed_rows(repo):
+    await repo.record_orchestrator_email(_row(msg="<ok@x>", success=True))
+    await repo.record_orchestrator_email(_row(msg="<bad@x>", success=False))
+    threads = await repo.list_orchestrator_email_threads(
+        "d1", "john@corp.com", "sarah@corp.com",
+    )
+    assert {t["message_id"] for t in threads} == {"<ok@x>"}
+
+
+@pytest.mark.asyncio
+async def test_prune_caps_per_decky(repo):
+    # Insert 5 rows on d1 with strictly-increasing timestamps so the
+    # prune's "newest-first keep, drop the rest" deterministically picks
+    # the older two.
+    base = datetime.now(timezone.utc) - timedelta(hours=10)
+    for i in range(5):
+        await repo.record_orchestrator_email(
+            _row(msg=f"<m{i}@x>", ts=base + timedelta(minutes=i))
+        )
+    # Cap at 3 — expect 2 deleted.
+    deleted = await repo.prune_orchestrator_emails(per_decky_cap=3)
+    assert deleted == 2
+    remaining = await repo.list_orchestrator_emails()
+    assert len(remaining) == 3
+    # The three newest survived.
+    assert {r["message_id"] for r in remaining} == {"<m2@x>", "<m3@x>", "<m4@x>"}