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- #253: /stale-docs - Flag outdated documentation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/pr-review/commands/pr-review.md

@@ -46,14 +46,16 @@ Collect findings from all agents, each with:
 
 ### Step 4: Filter by Confidence
 
-Only display findings with confidence >= 0.5:
+Filter findings based on `PR_REVIEW_CONFIDENCE_THRESHOLD` (default: 0.7):
 
 | Confidence | Label | Description |
 |------------|-------|-------------|
 | 0.9 - 1.0 | HIGH | Definite issue, must address |
 | 0.7 - 0.89 | MEDIUM | Likely issue, should address |
 | 0.5 - 0.69 | LOW | Possible concern, consider addressing |
-| < 0.5 | (suppressed) | Too uncertain to report |
+| < threshold | (filtered) | Below configured threshold |
+
+**Note:** With the default threshold of 0.7, only MEDIUM and HIGH confidence findings are shown. Adjust `PR_REVIEW_CONFIDENCE_THRESHOLD` to include more or fewer findings.
 
 ### Step 5: Generate Report
 
@@ -135,5 +137,5 @@ Full review report with:
 
 | Variable | Default | Description |
 |----------|---------|-------------|
-| `PR_REVIEW_CONFIDENCE_THRESHOLD` | `0.5` | Minimum confidence to report |
+| `PR_REVIEW_CONFIDENCE_THRESHOLD` | `0.7` | Minimum confidence to report (0.0-1.0) |
 | `PR_REVIEW_AUTO_SUBMIT` | `false` | Auto-submit to Gitea |