Quality-improve 10 v7.0.0-era engineering skills

Applies three consistent fixes across the v7.0.0 batch:
- Rename `## Output Structure` → `## Output Format` for consistency
- Wrap output template in `---` document separators (code-review-checklist,
  debugging-log-analyser needed full structural upgrade; remaining 8 already
  had the wrapper)
- Remove `## Example Trigger Phrases` section from all 10 skills

Skills updated: code-review-checklist, debugging-log-analyser,
changelog-generator, pr-description-writer, system-design-interview,
test-strategy-doc, runbook-writer, incident-postmortem, api-docs-writer,
architecture-decision-record

Both `skills/` and `plugins/pm-engineering/skills/` copies synced.

https://claude.ai/code/session_01C3HwChrccJd145vJ6Z7ajF

plugins/pm-engineering/skills/architecture-decision-record/SKILL.md

@@ -18,7 +18,7 @@ Ask the user for these if not provided:
 - **Status** (Proposed / Accepted / Deprecated / Superseded)
 - **Author and date**
 
-## Output Structure
+## Output Format
 
 ---
 
@@ -108,10 +108,3 @@ For each option, produce:
 - [ ] Decision is stated in plain language in the Decision section
 - [ ] Risks section identifies what would invalidate this decision
 - [ ] Written for someone with no prior context on this decision
-
-## Example Trigger Phrases
-
-- "Write an ADR for using [technology]"
-- "Document our decision to [architectural choice]"
-- "Create an architecture decision record for [topic]"
-- "Help me write up why we chose [option] over [alternative]"