feat(plugins): implement Sprint 4 commands (#241-#258)

Sprint 4 - Plugin Commands implementation adding 18 new user-facing
commands across 8 plugins as part of V5.2.0 Plugin Enhancements.

**projman:**
- #241: /sprint-diagram - Mermaid visualization of sprint issues

**pr-review:**
- #242: Confidence threshold config (PR_REVIEW_CONFIDENCE_THRESHOLD)
- #243: /pr-diff - Formatted diff with inline review comments

**data-platform:**
- #244: /data-quality - DataFrame quality checks (nulls, duplicates, outliers)
- #245: /lineage-viz - dbt lineage as Mermaid diagrams
- #246: /dbt-test - Formatted dbt test runner

**viz-platform:**
- #247: /chart-export - Export charts to PNG/SVG/PDF via kaleido
- #248: /accessibility-check - Color blind validation (WCAG contrast)
- #249: /breakpoints - Responsive layout configuration

**contract-validator:**
- #250: /dependency-graph - Plugin dependency visualization

**doc-guardian:**
- #251: /changelog-gen - Generate changelog from conventional commits
- #252: /doc-coverage - Documentation coverage metrics
- #253: /stale-docs - Flag outdated documentation

**claude-config-maintainer:**
- #254: /config-diff - Track CLAUDE.md changes over time
- #255: /config-lint - 31 lint rules for CLAUDE.md best practices

**cmdb-assistant:**
- #256: /cmdb-topology - Infrastructure topology diagrams
- #257: /change-audit - NetBox audit trail queries
- #258: /ip-conflicts - Detect IP conflicts and overlaps

Closes #241, #242, #243, #244, #245, #246, #247, #248, #249,
#250, #251, #252, #253, #254, #255, #256, #257, #258

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

plugins/doc-guardian/commands/doc-coverage.md

@@ -0,0 +1,128 @@
+---
+description: Calculate documentation coverage percentage for functions and classes
+---
+
+# Documentation Coverage
+
+Analyze codebase to calculate documentation coverage metrics.
+
+## Process
+
+1. **Scan Source Files**
+   Identify all documentable items:
+
+   **Python:**
+   - Functions (def)
+   - Classes
+   - Methods
+   - Module-level docstrings
+
+   **JavaScript/TypeScript:**
+   - Functions (function, arrow functions)
+   - Classes
+   - Methods
+   - JSDoc comments
+
+   **Other Languages:**
+   - Adapt patterns for Go, Rust, etc.
+
+2. **Determine Documentation Status**
+   For each item, check:
+   - Has docstring/JSDoc comment
+   - Docstring is non-empty and meaningful (not just `pass` or `TODO`)
+   - Parameters are documented (for detailed mode)
+   - Return type is documented (for detailed mode)
+
+3. **Calculate Metrics**
+   ```
+   Coverage = (Documented Items / Total Items) * 100
+   ```
+
+   **Levels:**
+   - Basic: Item has any docstring
+   - Standard: Docstring describes purpose
+   - Complete: All parameters and return documented
+
+4. **Output Format**
+```
+## Documentation Coverage Report
+
+### Summary
+- Total documentable items: 156
+- Documented: 142
+- Coverage: 91.0%
+
+### By Type
+| Type | Total | Documented | Coverage |
+|------|-------|------------|----------|
+| Functions | 89 | 85 | 95.5% |
+| Classes | 23 | 21 | 91.3% |
+| Methods | 44 | 36 | 81.8% |
+
+### By Directory
+| Path | Total | Documented | Coverage |
+|------|-------|------------|----------|
+| src/api/ | 34 | 32 | 94.1% |
+| src/utils/ | 28 | 28 | 100.0% |
+| src/models/ | 45 | 38 | 84.4% |
+| tests/ | 49 | 44 | 89.8% |
+
+### Undocumented Items
+- [ ] src/api/handlers.py:45 `create_order()`
+- [ ] src/api/handlers.py:78 `update_order()`
+- [ ] src/models/user.py:23 `UserModel.validate()`
+```
+
+## Options
+
+| Flag | Description | Default |
+|------|-------------|---------|
+| `--path <dir>` | Scan specific directory | Project root |
+| `--exclude <glob>` | Exclude files matching pattern | `**/test_*,**/*_test.*` |
+| `--include-private` | Include private members (_prefixed) | false |
+| `--include-tests` | Include test files | false |
+| `--min-coverage <pct>` | Fail if below threshold | none |
+| `--format <fmt>` | Output format (table, json, markdown) | table |
+| `--detailed` | Check parameter/return docs | false |
+
+## Thresholds
+
+Common coverage targets:
+| Level | Coverage | Description |
+|-------|----------|-------------|
+| Minimal | 60% | Basic documentation exists |
+| Good | 80% | Most public APIs documented |
+| Excellent | 95% | Comprehensive documentation |
+
+## CI Integration
+
+Use `--min-coverage` to enforce standards:
+```bash
+# Fail if coverage drops below 80%
+claude /doc-coverage --min-coverage 80
+```
+
+Exit codes:
+- 0: Coverage meets threshold (or no threshold set)
+- 1: Coverage below threshold
+
+## Example Usage
+
+```
+/doc-coverage
+/doc-coverage --path src/
+/doc-coverage --min-coverage 85 --exclude "**/generated/**"
+/doc-coverage --detailed --include-private
+```
+
+## Language Detection
+
+File extensions mapped to documentation patterns:
+| Extension | Language | Doc Format |
+|-----------|----------|------------|
+| .py | Python | Docstrings (""") |
+| .js, .ts | JavaScript/TypeScript | JSDoc (/** */) |
+| .go | Go | // comments above |
+| .rs | Rust | /// doc comments |
+| .rb | Ruby | # comments, YARD |
+| .java | Java | Javadoc (/** */) |