fix(marketplace): remove integrates_with field (schema violation)

Claude Code's marketplace schema does not support custom fields.
The `integrates_with` field on data-platform and viz-platform caused:
"Invalid schema: plugins.9: Unrecognized key: integrates_with"

This reverts the schema extension while keeping the validate_workflow_integration
MCP tool functional (it reads from plugin.json files directly, not marketplace.json).

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

CHANGELOG.md

@@ -9,11 +9,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Added
 - **contract-validator**: New `validate_workflow_integration` MCP tool — validates domain plugins expose required advisory interfaces (gate command, review command, advisory agent)
 - **contract-validator**: New `MISSING_INTEGRATION` issue type for workflow integration validation
-- **marketplace.json**: `integrates_with` field on viz-platform and data-platform declaring projman integration metadata
 
 ### Fixed
 - `scripts/setup.sh` banner version updated from v5.1.0 to v5.7.1
 
+### Reverted
+- **marketplace.json**: Removed `integrates_with` field — Claude Code schema does not support custom plugin fields (causes marketplace load failure)
+
 ---
 
 ## [5.7.0] - 2026-02-02