feat: optimize skills + add pipeline handoff chaining across 9 skills

asr-transcribe-to-text:
- Add local MLX transcription path (macOS Apple Silicon, 15-27x realtime)
- Add bundled script transcribe_local_mlx.py with max_tokens=200000
- Add local_mlx_guide.md with benchmarks and truncation trap docs
- Auto-detect platform and recommend local vs remote mode
- Fix audio extraction format (MP3 → WAV 16kHz mono PCM)
- Add Step 5: recommend transcript-fixer after transcription

transcript-fixer:
- Optimize SKILL.md from 289 → 153 lines (best practices compliance)
- Move FALSE_POSITIVE_RISKS (40 lines) to references/false_positive_guide.md
- Move Example Session to references/example_session.md
- Improve description for better triggering (226 → 580 chars)
- Add handoff to meeting-minutes-taker

skill-creator:
- Add "Pipeline Handoff" pattern to Skill Writing Guide
- Add pipeline check reminder in Step 4 (Edit the Skill)

Pipeline handoffs added to 8 skills forming 6 chains:
- youtube-downloader → asr-transcribe-to-text → transcript-fixer → meeting-minutes-taker → pdf/ppt-creator
- deep-research → fact-checker → pdf/ppt-creator
- doc-to-markdown → docs-cleaner / fact-checker
- claude-code-history-files-finder → continue-claude-work

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

skill-creator/SKILL.md

@@ -288,6 +288,47 @@ competitors-analysis (fork, specialist)
 3. Each skill has a single responsibility — don't mix orchestration with execution
 4. Share methodology via references (e.g., checklists, templates), not by duplicating code
 
+##### Pipeline Handoff (Sequential Skill Chaining)
+
+Beyond orchestrator/specialist composition, skills often form **sequential pipelines** where one skill's output is the next skill's input. Each skill should proactively suggest the logical next step after completing its work.
+
+**Pattern: "Next Step" section at the end of SKILL.md**
+
+```markdown
+## Next Step: [Action Description]
+
+After [this skill completes], suggest the natural next skill:
+
+\```
+[Summary of what was just accomplished].
+
+Options:
+A) [Next skill] — [one-line reason] (Recommended)
+B) [Alternative skill] — [when this is better]
+C) No thanks — [the current output is sufficient]
+\```
+```
+
+**Real-world pipeline examples:**
+
+```
+youtube-downloader → asr-transcribe-to-text → transcript-fixer → meeting-minutes-taker → pdf-creator
+deep-research → fact-checker → ppt-creator
+doc-to-markdown → docs-cleaner
+claude-code-history-files-finder → continue-claude-work
+```
+
+**Rules for pipeline handoff:**
+1. Every handoff is **opt-in** via AskUserQuestion — never auto-invoke the next skill without asking
+2. Suggest only when the output naturally feeds into another skill — don't force connections
+3. Include a "No thanks" option — the user may not need the full pipeline
+4. The suggestion should explain **why** the next step helps (e.g., "ASR output typically contains recognition errors")
+5. Keep it to 1-2 recommendations max — too many choices cause decision fatigue
+
+**When to add a handoff:** Ask "does this skill's output commonly become another skill's input?" If yes, add a "Next Step" section. If the connection is rare or forced, don't add one.
+
+**Anti-pattern:** Chaining skills that don't share a natural data flow. `pdf-creator → youtube-downloader` makes no sense. The pipeline must follow the user's actual workflow.
+
 ##### Auto-Detection Over Manual Flags
 
 **Never add manual flags for capabilities that can be auto-detected.** Instead of requiring users to pass `--with-codex` or `--verbose`, detect capabilities at runtime:
@@ -854,6 +895,8 @@ When editing, remember that the skill is being created for another instance of C
 
 **When updating an existing skill**: Scan all existing reference files to check if they need corresponding updates.
 
+**Pipeline check**: Consider whether this skill's output naturally feeds into another skill. If so, add a "Next Step" handoff section (see "Pipeline Handoff" in the Skill Writing Guide). Also check if any existing skill should chain *into* this one.
+
 ### Step 5: Sanitization Review (Optional)
 
 Use **AskUserQuestion** before executing this step: