feat(J): Phase J Self-Improvement Plugin — controlled improvement loop

- New self_improvement plugin: models, services, routes, plugin
- 4 SQLAlchemy models: ImprovementSignal, ImprovementPattern, ImprovementProposal, ImpactMeasurement
- Migration 0132: 4 tables with RLS
- Services: collect_signals, detect_patterns, create_proposal, evaluate_proposal, request_approval, activate_proposal, rollback_proposal, measure_impact
- 11 API routes under /api/v1/improvement/
- Frontend: improvement.ts API client, ImprovementPanel.tsx in AISidebar proactive tab
- 24/24 integration tests pass
- Fix: __init__.py imports Plugin class for discover_builtins() (self_improvement + knowledge)
- Fix: automation plugin register_plugin_contributions skips when no tenant exists

tests/conftest.py

@@ -82,6 +82,13 @@ from app.models.plugin_allowlist import PluginAllowlist  # noqa: F401
 from app.plugins.builtins.wiki.models import WikiArticle, WikiArticleVersion, WikiCategory  # noqa: F401
 # Knowledge plugin models — new plugin, ensure table is created in test-DB
 from app.plugins.builtins.knowledge.models import KnowledgeExtraction  # noqa: F401
+# Self-improvement plugin models — new plugin, ensure tables are created in test-DB
+from app.plugins.builtins.self_improvement.models import (  # noqa: F401
+    ImprovementSignal,
+    ImprovementPattern,
+    ImprovementProposal,
+    ImpactMeasurement,
+)
 
 from app.plugins.registry import reset_registry_for_testing  # noqa: F401
 from app.core.permission_registry import init_permission_registry  # noqa: F401