Board Program LEARN context, ruff 0.16, and verb-rejection observability (#700)

* fix(board): LEARN decisions name the item, not its per-cycle index

A cycle's reject reasons are rendered into the NEXT cycle's exploration
prompt, but the ref recorded alongside each reason was the item's stored
id (item-0/item-1) — a per-cycle index that means something different
every cycle and appears nowhere the explorer can resolve. The reason
survived the loop; what it was about did not.

Record the item's title instead, via a shared learn_ref() helper (falls
back to the id when title-less, and reads target_task_title for Scales,
whose items name the live task they mutate).

* chore(lint): satisfy ruff 0.16 — keyword-only signatures and markdown formatting

The dev toolchain resolved ruff 0.16.0, which stabilises PLR0917 (too many
positional arguments) and formats python code blocks inside markdown. Both
fired repo-wide and neither had anything to do with the code they flagged.

- 36 signatures gain a `*` so their tail arguments are keyword-only, and
  the 104 call sites that passed them positionally are converted. mypy was
  the safety net for the static ones; the full suite caught nine more that
  only bind at runtime (the MCP tool functions, whose real callers already
  pass named JSON arguments).
- 28 markdown files reformatted by 0.16's code-block formatter.
- One RUF036 (`None` mid-union) autofixed in the GitLab provider.

* fix(gateway): log the reason when a verb rejects

A rejected envelope rides an HTTP 200, its body is never logged, and there
is no trace table — so in the access log a verb an agent could not satisfy
looks identical to one that worked. On 2026-07-25 four Board Programs
(Periscope, Sentinel, Scales, Barfly) each POSTed their propose verb three
or four times, persisted nothing, and left their exploration tasks PENDING;
the reason was unrecoverable afterwards, from the logs or from the agents'
own transcripts.

Log error/message/remediate/missing plus the calling agent at
envelope_to_response — the one chokepoint every v1 flow and do route
returns through. Success envelopes stay silent.

---------

Co-authored-by: Renn F <rennf93@users.noreply.github.com>

docs/rag/roles/head-marketing.md

@@ -69,9 +69,9 @@ propose_market_brief(
         {"claim": "...", "source_url": "https://...", "relevance": "..."},
         # 1-7 findings, source_url REQUIRED per finding — an uncited claim is rejected
     ],
-    threats=["..."],          # optional, up to 5
-    opportunities=["..."],    # optional, up to 5
-    positioning_note="...",   # optional
+    threats=["..."],  # optional, up to 5
+    opportunities=["..."],  # optional, up to 5
+    positioning_note="...",  # optional
 )
 ```
 
@@ -99,8 +99,12 @@ Quarterly cron, project-scoped (`projects.board_programs` contains `"mirror"`).
 propose_messaging_fixes(
     items=[
         {
-            "title": "...", "description": "...", "acceptance_criteria": ["..."],
-            "project_slug": "roboco-website", "team": "backend", "priority": 2,
+            "title": "...",
+            "description": "...",
+            "acceptance_criteria": ["..."],
+            "project_slug": "roboco-website",
+            "team": "backend",
+            "priority": 2,
             "evidence": "BOTH the drifted claim and the reality it contradicts — REQUIRED",
         },
         # 1-5 items
@@ -138,8 +142,8 @@ Cron every 2 days, org-scoped. The task carries a set of SCREENED candidate X co
 propose_conversation_replies(
     items=[
         {
-            "tweet_id": "...",     # REQUIRED — must be one of the candidate ids verbatim
-            "reply_body": "...",   # your voice, <=280 chars, no invented facts
+            "tweet_id": "...",  # REQUIRED — must be one of the candidate ids verbatim
+            "reply_body": "...",  # your voice, <=280 chars, no invented facts
             "rationale": "why this conversation is worth replying to",  # REQUIRED
         },
         # up to 5 items
@@ -166,7 +170,11 @@ The CEO acts via the panel/UI; you idle until the CEO decides.
 ## A2A
 
 ```python
-dm(recipient="product-owner", text="Market analysis for the launch — ...", task_id="...")
+dm(
+    recipient="product-owner",
+    text="Market analysis for the launch — ...",
+    task_id="...",
+)
 ```
 
 Skills: market_analysis