feat: add RAG corpus versioning and source policy backend

Part 1 — RAG Corpus Versioning:
- New DB table compliance_corpus_versions (migration 017)
- Go CorpusVersionStore with CRUD operations
- Assessment struct extended with corpus_version_id
- API endpoints: GET /rag/corpus-status, /rag/corpus-versions/:collection
- RAG routes (search, regulations) now registered in main.go
- Ingestion script registers corpus versions after each run
- Frontend staleness badge in SDK sidebar

Part 3 — Source Policy Backend:
- New FastAPI router with CRUD for allowed sources, PII rules,
  operations matrix, audit trail, stats, and compliance report
- SQLAlchemy models for all source policy tables (migration 001)
- Frontend API base corrected from edu-search:8088/8089 to
  backend-compliance:8002/api

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-compliance/app/(sdk)/sdk/source-policy/page.tsx

@@ -3,8 +3,8 @@
 /**
  * Source Policy Management Page (SDK Version)
  *
- * Whitelist-based data source management for edu-search-service.
- * For auditors: Full audit trail for all changes.
+ * Whitelist-based data source management for compliance RAG corpus.
+ * Controls which legal sources may be used, PII rules, and audit trail.
  */
 
 import { useState, useEffect } from 'react'
@@ -15,14 +15,14 @@ import { OperationsMatrixTab } from '@/components/sdk/source-policy/OperationsMa
 import { PIIRulesTab } from '@/components/sdk/source-policy/PIIRulesTab'
 import { AuditTab } from '@/components/sdk/source-policy/AuditTab'
 
-// API base URL for edu-search-service
+// API base URL for backend-compliance
 const getApiBase = () => {
-  if (typeof window === 'undefined') return 'http://localhost:8088'
+  if (typeof window === 'undefined') return 'http://localhost:8002/api'
   const hostname = window.location.hostname
   if (hostname === 'localhost' || hostname === '127.0.0.1') {
-    return 'http://localhost:8088'
+    return 'http://localhost:8002/api'
   }
-  return `https://${hostname}:8089`
+  return `https://${hostname}:8002/api`
 }
 
 interface PolicyStats {