[Workflow] Wire tooling observations into workflow completion steps

[athola]

Context

During a /fix-pr run on PR #301, the workflow completed successfully
but had no mechanism to capture and post observations about the
night-market tooling itself (skills, agents, commands, hooks).

Observation

Current behavior: Workflows like fix-pr, do-issue, execute-plan
complete their task and post results to the repo (comments, commits).
Observations about the tooling used during the workflow are lost
unless manually noted.

Desired behavior: Workflow completion steps (Step 6 in fix-pr,
final phase in do-issue, etc.) should include a reflection checkpoint:
"Did I observe friction, bugs, or improvement opportunities in the
tooling itself?" If yes, post to GitHub Discussions in the Learnings
category.

Existing Infrastructure

The abstract plugin already has:

• post_learnings_to_discussions.py - posts to Learnings category
• auto_promote_learnings.py - promotes high-value learnings
• aggregate_learnings_daily.py - daily aggregation hook

The gap is wiring -- workflow commands don't call these scripts
at completion.

Proposed Improvement

Add a "tooling reflection" step to workflow completion phases:

1. After validation passes, check: were there tooling observations?
2. If yes, format as a learning and post via
   post_learnings_to_discussions.py
3. Categories: skill behavior, agent coordination, hook timing,
   command UX friction

Affected Components

Component	File	Change
fix-pr Step 6	sanctum/skills/fix-pr-modules/steps/6-complete.md	Add reflection step
do-issue completion	sanctum/skills/do-issue/SKILL.md	Add reflection step
workflow-improvement	sanctum/skills/workflow-improvement/SKILL.md	Already posts -- verify wiring

Complexity

Low (wiring existing infrastructure, no new code needed).
Defer to next branch -- current branch at RED ZONE (19K lines).

Source

/fix-workflow retrospective on /fix-pr PR #301 run (2026-03-15).

[athola]

Tracking issue: #573