[sweep] strip Fxxx audit-ID tokens + trim bloated comments/docstrings + add behavior-change docs

Post-audit sweep over the 135 audit-fix commits since 19a474d3:

1. Stripped every # Fxxx: audit-ID token from comments AND every Fxxx token
   from docstring openings across 211 blocks / ~626 lines. The CEO flagged
   these twice: audit-issue IDs in code confuse future devs/agents. The
   descriptive text is preserved; only the Fxxx token is removed (and bloated
   narrative blocks trimmed to 1-3 lines keeping the one non-obvious invariant).
2. Trimmed bloated comments/docstrings to the concise standard (1-3 lines).
3. Added missing behavior-change docs for the audit-fix batch: prompts/roles
   (documenter, pr_reviewer, qa), user-facing docs (api auth, websockets,
   agent-gateway, megatask, merge-model, task-lifecycle, grok, resilience,
   conventions, panel, security, troubleshooting), and the RAG corpus (cell-pm,
   main-pm, pr-reviewer, qa roles; conventions; messaging-tools; escalation;
   megatask; task-claiming workflows).

Comment/docstring/prose ONLY — zero code-line edits (verified: the diff
contains no def/class/return/if/for/await/assignment/call lines). Gates green:
ruff format + ruff check clean, mypy clean on roboco/. The only pytest failures
are the pre-existing sync_branch tracing-decision gap (B1, 250be5c2) — not
sweep-caused and tracked separately.

tests/integration/test_task_service_lifecycle_misc.py

@@ -453,14 +453,10 @@ async def test_create_work_session_no_project_returns_none(
 async def test_create_work_session_delegates_to_service_create(
     task_setup: dict, db_session: AsyncSession, monkeypatch: pytest.MonkeyPatch
 ) -> None:
-    """F113: the claim path must create the WorkSession through the validated
-    ``WorkSessionService.create`` (the single source of truth), not construct a
-    ``WorkSessionTable`` directly. Two divergent creation sites had drifted and
-    bypassed the service-layer validation (existing-active check, supersede
-    invariant, project/task existence). Routing through ``create`` collapses
-    them to one validated path. The derived target_branch (parent branch for
-    subtasks, project default for roots) is passed in via ``WorkSessionCreate``.
-    """
+    """The claim path must create the WorkSession via ``WorkSessionService.create``
+    (single source of truth) rather than constructing a ``WorkSessionTable``
+    directly, so service-layer validation (existing-active check, supersede
+    invariant) is not bypassed."""
     svc = task_setup["svc"]
     task = await svc.create(_req(task_setup))
     task.branch_name = "feature/backend/delegate"