refactor(linkedin-studio): S29e terminology-scrub — rename thought-leadership-angles.md -> content-angles.md + all pointers

Final sub-pass of the S29 plugin-wide terminology scrub. The canonical reference file is
renamed and every functional pointer updated atomically in one commit. The file's in-file
title/headers were already FORM A-scrubbed in S29c (H1 reads "Content Angles"), so S29e is a
pure rename + pointer update — no FORM A remained in the file.

Rename: references/thought-leadership-angles.md -> references/content-angles.md (git mv).

Pointers updated (17 files, 29 occurrences) — token "thought-leadership-angles" -> "content-angles":
- references/ (2): ai-content-framework, glossary
- agents/ (7): content-repurposer, strategy-advisor, network-builder, content-planner,
  trend-spotter, video-scripter, differentiation-checker
- commands/ (6): pipeline, video, post, competitive, react, batch
- skills/ (1): linkedin-content-creation/SKILL
- docs/ (1, forward-looking): integration-test-guide

Left URØRT per the standing S29 decision (history = honest record of a past state, not a
runtime load): CHANGELOG.md, docs/hardening/log.md, docs/hardening/plan.md. STATE.md untouched
here (rewritten at session end).

Verify: no thought-leadership-angles* file remains; references/content-angles.md present; zero
residual "thought-leadership-angles" in commands/agents/references/skills/integration-test-guide;
structure gate scripts/test-runner.sh 81/0/0 exit 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016qgzo6rxthw7KuxHjn5vyE

docs/integration-test-guide.md

@@ -20,7 +20,7 @@ Before testing, ensure:
 1. Run `/linkedin:pipeline`
 2. Verify Step 0 loads: state file read, status displayed (posts/week, streak)
 3. Choose "Generate ideas for me" when prompted
-4. Verify 3 topic suggestions appear, drawn from `thought-leadership-angles.md`
+4. Verify 3 topic suggestions appear, drawn from `content-angles.md`
 5. Select a topic → verify angle selection (2-3 options)
 6. Choose format → verify draft follows structure (hook/context/insight/implication/CTA)
 7. Verify optimization checks run: