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_events.py

@@ -0,0 +1,72 @@
+"""events.to_row / topic_for / event_type_for."""
+from __future__ import annotations
+
+from decnet.bus import topics as _topics
+from decnet.orchestrator.drivers.base import ActivityResult
+from decnet.orchestrator.emailgen import events
+from decnet.orchestrator.emailgen.personas import EmailPersona
+from decnet.orchestrator.emailgen.scheduler import EmailAction
+
+
+def _persona(email="john@corp.com"):
+    return EmailPersona(
+        name="John", email=email, role="COO", tone="formal",
+        mannerisms=[], language="en",
+    )
+
+
+def _action():
+    return EmailAction(
+        mail_decky_uuid="d1",
+        mail_decky_name="mailhost",
+        mail_decky_services=("imap",),
+        sender=_persona(),
+        recipient=_persona(email="sarah@corp.com"),
+        thread_id="thr1",
+        parent_message_id=None,
+        references="",
+        subject_hint=None,
+        parent_excerpt=None,
+        context_hint="Q3 budget",
+        is_reply=False,
+    )
+
+
+def test_to_row_pulls_message_id_subject_from_payload():
+    res = ActivityResult(
+        success=True,
+        payload={
+            "message_id": "<m1@corp.com>",
+            "subject": "Q3 budget",
+            "language": "en",
+            "eml_path": "/var/spool/decnet-emails/thr1/m1.eml",
+            "model": "llama3.1",
+        },
+    )
+    row = events.to_row(_action(), res)
+    assert row["mail_decky_uuid"] == "d1"
+    assert row["thread_id"] == "thr1"
+    assert row["message_id"] == "<m1@corp.com>"
+    assert row["subject"] == "Q3 budget"
+    assert row["sender_email"] == "john@corp.com"
+    assert row["recipient_email"] == "sarah@corp.com"
+    assert row["language"] == "en"
+    assert row["eml_path"].endswith(".eml")
+    assert row["success"] is True
+    assert row["payload"]["model"] == "llama3.1"
+
+
+def test_to_row_falls_back_to_persona_language():
+    res = ActivityResult(success=True, payload={})
+    row = events.to_row(_action(), res)
+    assert row["language"] == "en"
+    assert row["message_id"] == ""
+
+
+def test_topic_for_uses_orchestrator_email_root():
+    topic = events.topic_for(_action())
+    assert topic == f"orchestrator.{_topics.ORCHESTRATOR_EMAIL}.d1"
+
+
+def test_event_type_for_returns_email_constant():
+    assert events.event_type_for(_action()) == _topics.ORCHESTRATOR_EMAIL