[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.

docs/rag/workflows/task-claiming.md

@@ -41,7 +41,7 @@ The claim verb both claims and starts the task — there is no separate `start`
 
 ## Claiming Rules
 
-- **One at a time (workers only)**: Developers, QA, and documenters can't hold multiple in-progress tasks at once. **PM coordinators are exempt** — a Main / Cell PM plans and delegates many roots in parallel, so it may hold several at once; only a real upstream **sequence dependency** (an unfinished task it depends on) holds one of its roots back.
+- **One at a time (workers only)**: Developers, QA, and documenters can't hold multiple in-progress tasks at once. A **blocked** task still counts as active — a blocked dev cannot `claim` a second task; unblock or `unclaim` first. **PM coordinators are exempt** — a Main / Cell PM plans and delegates many roots in parallel, so it may hold several at once; only a real upstream **sequence dependency** (an unfinished task it depends on) holds one of its roots back.
 - **Self-review prevention**: QA cannot `claim_review` tasks they developed
 - **Self-documentation prevention**: Documenter cannot claim tasks they developed
 - **Branch requirement**: Branch auto-created on `i_will_work_on`