[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_messaging_service.py

@@ -1198,7 +1198,7 @@ async def _seed_messages_same_timestamp(
 async def test_get_messages_compound_before_cursor_no_skip_on_equal_timestamps(
     msg_setup: dict,
 ) -> None:
-    """Equal-timestamp messages must not be skipped across pages (F106).
+    """Equal-timestamp messages must not be skipped across pages.
 
     With a strict ``timestamp < before`` cursor and ``order_by(timestamp.desc())``,
     messages sharing the page's last timestamp are cut by ``limit`` on page 1
@@ -1239,7 +1239,7 @@ async def test_get_messages_compound_after_cursor_no_skip_on_equal_timestamps(
 ) -> None:
     """Forward pagination (``after``) with the compound ``(timestamp, id)``
     cursor tie-breaks on id so newer-direction pagination across equal
-    timestamps skips nothing either (F106).
+    timestamps skips nothing either.
 
     With a strict ``timestamp > after`` cursor, every row sharing the cursor's
     timestamp is EXCLUDED — so forward-paginating from a middle message would