feat(contract-validator): add validate_workflow_integration tool (v5.7.1)

Domain Advisory Pattern Hardening - patch release to close gaps from v5.6.0/v5.7.0:

## Added
- New `validate_workflow_integration` MCP tool validates domain plugins expose
  required advisory interfaces (gate command, review command, advisory agent)
- New `MISSING_INTEGRATION` issue type for workflow integration validation
- New `WorkflowIntegrationResult` Pydantic model for structured validation output
- `integrates_with` field on viz-platform and data-platform in marketplace.json
  declaring projman integration metadata
- 4 new test cases for workflow integration validation

## Fixed
- scripts/setup.sh banner version updated from v5.1.0 to v5.7.1

## Documentation
- Updated mcp-tools-reference.md with new tool
- Updated validation-rules.md with Workflow Integration Checks section
- Added /design-gate, /design-review, /data-gate, /data-review to COMMANDS-CHEATSHEET
- Added contract-validator to CONFIGURATION.md plugin table
- Updated README.md Contract Validator tools table

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

plugins/contract-validator/skills/validation-rules.md

@@ -30,6 +30,13 @@ Rules for validating plugin compatibility and agent definitions.
 3. Check for orphaned data references
 4. Ensure required data is available at each step
 
+### Workflow Integration Checks
+1. Gate command exists in plugin's commands/ directory
+2. Gate command produces binary PASS/FAIL output
+3. Review command exists (WARNING if missing, not ERROR)
+4. Advisory agent exists referencing the domain label
+- Severity: ERROR for missing gate, WARNING for missing review/agent
+
 ## Severity Levels
 
 | Level | Meaning | Action |
@@ -46,6 +53,8 @@ Rules for validating plugin compatibility and agent definitions.
 | Data flow gap | Producer not called before consumer | Reorder workflow steps |
 | Name conflict | Two plugins use same command | Rename one command |
 | Orphan reference | Data produced but never consumed | Remove or use the data |
+| Missing gate command | Domain plugin lacks /X-gate command | Create commands/{domain}-gate.md |
+| Missing advisory agent | Domain plugin has no reviewer agent | Create agents/{domain}-advisor.md |
 
 ## MCP Tools
 
@@ -54,4 +63,5 @@ Rules for validating plugin compatibility and agent definitions.
 | `validate_compatibility` | Check two plugins for conflicts |
 | `validate_agent_refs` | Check agent tool references |
 | `validate_data_flow` | Verify data flow sequences |
+| `validate_workflow_integration` | Check domain plugin advisory interfaces |
 | `list_issues` | Filter issues by severity or type |