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- #253: /stale-docs - Flag outdated documentation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/contract-validator/README.md

@@ -19,6 +19,7 @@ Contract-validator solves these by parsing plugin interfaces and validating comp
 - **Agent Extraction**: Parse CLAUDE.md Four-Agent Model tables and Agents sections
 - **Compatibility Checks**: Pairwise validation between all plugins in a marketplace
 - **Data Flow Validation**: Verify agent tool sequences have valid data producers/consumers
+- **Dependency Visualization**: Generate Mermaid flowcharts showing plugin relationships
 - **Comprehensive Reports**: Markdown or JSON reports with actionable suggestions
 
 ## Installation
@@ -44,6 +45,7 @@ pip install -r requirements.txt
 | `/validate-contracts` | Full marketplace compatibility validation |
 | `/check-agent` | Validate single agent definition |
 | `/list-interfaces` | Show all plugin interfaces |
+| `/dependency-graph` | Generate Mermaid flowchart of plugin dependencies |
 
 ## Agents
 
@@ -106,6 +108,16 @@ pip install -r requirements.txt
 # Data Flow: No issues detected
 ```
 
+```
+/dependency-graph
+
+# Output: Mermaid flowchart showing:
+# - Plugins grouped by shared MCP servers
+# - Data flow from data-platform to viz-platform
+# - Required vs optional dependencies
+# - Command counts per plugin
+```
+
 ## Issue Types
 
 | Type | Severity | Description |