Add RAG semantic search and proactive event notifications

Implement hybrid knowledge search using Cloudflare Vectorize + Workers AI
embeddings (bge-base-en-v1.5, 768d) merged with existing D1 LIKE queries,
with graceful degradation when Vectorize is unavailable. Add admin API
endpoints for batch/single article indexing.

Add 4 proactive notification cron jobs: server status changes, deposit
confirmation/rejection alerts, pending payment reminders (1h+), and bank
deposit matching notifications — all with DB-column-based deduplication.

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

src/types.ts

@@ -27,6 +27,8 @@ export interface Env {
   CACHE_KV: KVNamespace;
   // R2
   R2_BUCKET: R2Bucket;
+  // Vectorize
+  VECTORIZE?: VectorizeIndex;
 }
 
 // ============================================
@@ -296,6 +298,8 @@ export interface KnowledgeArticle {
   tags: string | null;
   language: string;
   is_active: number;
+  embedding_indexed: number;
+  embedding_indexed_at: string | null;
   created_at: string;
   updated_at: string;
 }