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- #253: /stale-docs - Flag outdated documentation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/claude-config-maintainer/README.md

@@ -37,6 +37,33 @@ Create a new CLAUDE.md tailored to your project.
 /config-init
 ```
 
+### `/config-diff`
+Show differences between current CLAUDE.md and previous versions.
+
+```
+/config-diff                    # Compare working copy vs last commit
+/config-diff --commit=abc1234   # Compare against specific commit
+/config-diff --from=v1.0 --to=v2.0  # Compare two commits
+/config-diff --section="Critical Rules"  # Focus on specific section
+```
+
+### `/config-lint`
+Lint CLAUDE.md for common anti-patterns and best practices.
+
+```
+/config-lint                    # Run all lint checks
+/config-lint --fix              # Auto-fix fixable issues
+/config-lint --rules=security   # Check only security rules
+/config-lint --severity=error   # Show only errors
+```
+
+**Lint Rule Categories:**
+- **Security (SEC)** - Hardcoded secrets, paths, credentials
+- **Structure (STR)** - Header hierarchy, required sections
+- **Content (CNT)** - Contradictions, duplicates, vague rules
+- **Format (FMT)** - Consistency, code blocks, whitespace
+- **Best Practice (BPR)** - Missing Quick Start, Critical Rules sections
+
 ## Best Practices
 
 A good CLAUDE.md should be: