refactor(clarity-assist): extract skills from commands

Extract shared knowledge from clarify.md and quick-clarify.md into
reusable skill files:
- 4d-methodology.md: Core 4-phase clarification process
- nd-accommodations.md: Neurodivergent-friendly question patterns
- clarification-techniques.md: Anti-patterns and question templates
- escalation-patterns.md: Mode switching guidelines

Commands slimmed from 149/96 lines to 44/49 lines respectively.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/pr-review/skills/pr-analysis.md

@@ -0,0 +1,135 @@
+# PR Analysis Patterns
+
+## Data Collection
+
+### Step 1: Fetch PR Metadata
+
+```
+get_pull_request(pr_number) returns:
+- title, description
+- author, assignees
+- base/head branches
+- status (open, closed, merged)
+- labels, milestone
+- created_at, updated_at
+```
+
+### Step 2: Get Code Changes
+
+```
+get_pr_diff(pr_number) returns:
+- Unified diff format
+- File paths with +/- indicators
+- Hunk headers with line numbers
+```
+
+### Step 3: Get Existing Feedback
+
+```
+get_pr_comments(pr_number) returns:
+- Review comments with file/line
+- General comments
+- Author, timestamp
+- Thread context (replies)
+```
+
+## Change Analysis
+
+### Categorize Changes
+
+| Pattern | Category |
+|---------|----------|
+| New files only | Feature addition |
+| Modified test files | Test updates |
+| Modified + deleted | Refactoring |
+| Single file fix | Bug fix |
+| Config/docs only | Infrastructure |
+
+### Calculate Statistics
+
+- Files changed count
+- Lines added/removed
+- Net change (+added - removed)
+- New vs modified vs deleted files
+
+### Identify Key Files
+
+Priority order:
+1. Security-sensitive (`auth`, `crypto`, `sql`)
+2. API endpoints
+3. Database migrations
+4. Core business logic
+5. Utilities and helpers
+6. Tests
+7. Documentation
+
+## Risk Assessment
+
+### Scope Assessment
+
+| Files Changed | Lines Changed | Scope |
+|---------------|---------------|-------|
+| 1-3 | < 50 | Small |
+| 4-10 | 50-200 | Medium |
+| 10+ | 200+ | Large |
+
+### Risk Indicators
+
+| Indicator | Risk Level |
+|-----------|------------|
+| Security-sensitive files | High |
+| Database migrations | High |
+| API changes | Medium |
+| New dependencies | Medium |
+| Test-only changes | Low |
+| Docs-only changes | Low |
+
+## Summary Generation
+
+### Quick Summary Template
+
+```
+This PR [adds|updates|fixes|removes] [feature/component]:
+
+1. **[Category 1]**
+   - Change description
+
+2. **[Category 2]**
+   - Change description
+
+Key files:
+- path/to/important/file.ts (+lines)
+```
+
+### Assessment Template
+
+```
+Scope: [Small|Medium|Large]
+Risk: [Low|Medium|High]
+Recommendation: [/pr-review suggested | Looks good to merge]
+```
+
+## Annotated Diff Display
+
+### Format
+
+```
+File: src/api/users.ts (+85 / -12)
+----------------------------------------
+
+@@ -42,6 +42,15 @@ function description
+   42 |   existing line
+   43 |
+   44 |-  removed line
+      |   [COMMENT by @user (time ago)]
+      |   Comment text here
+   45 |+  added line
+   46 |+  another added line
+```
+
+### Comment Overlay
+
+Position comments at their file/line locations:
+- Show commenter username and time
+- Include reply threads
+- Mark resolved vs open