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>

schema.sql

@@ -52,6 +52,8 @@ CREATE TABLE IF NOT EXISTS transactions (
   reference_id INTEGER,
   confirmed_by INTEGER,
   confirmed_at DATETIME,
+  status_notified_at DATETIME,
+  reminder_sent_at DATETIME,
   created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
   FOREIGN KEY (user_id) REFERENCES users(id),
   FOREIGN KEY (confirmed_by) REFERENCES users(id)
@@ -68,6 +70,7 @@ CREATE TABLE IF NOT EXISTS bank_notifications (
   transaction_time DATETIME,
   raw_message TEXT,
   matched_transaction_id INTEGER,
+  match_notified_at DATETIME,
   created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
   FOREIGN KEY (matched_transaction_id) REFERENCES transactions(id)
 );
@@ -107,6 +110,7 @@ CREATE TABLE IF NOT EXISTS servers (
   provisioned_at DATETIME,
   terminated_at DATETIME,
   expires_at DATETIME,
+  last_notified_status TEXT,
   created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
   updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
   FOREIGN KEY (user_id) REFERENCES users(id)
@@ -194,6 +198,8 @@ CREATE TABLE IF NOT EXISTS knowledge_articles (
   tags TEXT,
   language TEXT DEFAULT 'ko',
   is_active INTEGER DEFAULT 1,
+  embedding_indexed INTEGER DEFAULT 0,
+  embedding_indexed_at DATETIME,
   created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
   updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );
@@ -335,3 +341,21 @@ CREATE INDEX IF NOT EXISTS idx_onboarding_expires ON onboarding_sessions(expires
 CREATE INDEX IF NOT EXISTS idx_troubleshoot_expires ON troubleshoot_sessions(expires_at);
 CREATE INDEX IF NOT EXISTS idx_asset_expires ON asset_sessions(expires_at);
 CREATE INDEX IF NOT EXISTS idx_billing_expires ON billing_sessions(expires_at);
+
+----------------------------------------------------------------------
+-- Notification Tracking Columns (Migration)
+----------------------------------------------------------------------
+
+-- servers: 상태 변경 알림 추적
+-- ALTER TABLE servers ADD COLUMN last_notified_status TEXT;
+
+-- transactions: 입금 승인/거부 알림 + 리마인더 추적
+-- ALTER TABLE transactions ADD COLUMN status_notified_at DATETIME;
+-- ALTER TABLE transactions ADD COLUMN reminder_sent_at DATETIME;
+
+-- bank_notifications: 매칭 알림 추적
+-- ALTER TABLE bank_notifications ADD COLUMN match_notified_at DATETIME;
+
+-- Knowledge articles: 임베딩 인덱싱 추적
+-- ALTER TABLE knowledge_articles ADD COLUMN embedding_indexed INTEGER DEFAULT 0;
+-- ALTER TABLE knowledge_articles ADD COLUMN embedding_indexed_at DATETIME;