feat(storage): migrate config, dedup and delivery state to D1

- Move oversized queue payloads from KV to R2 (PAYLOAD binding, webhooks/YYYY/MM/DD/*.json, KV queue:payload:* fallback)
- Persist routes/groups to D1 (d1_routes/d1_groups) with memory -> KV -> D1 three-tier cache, seeded from legacy KV config keys
- Move webhook dedup (dedup_keys), delivery state (delivery_state) and message tracking (message_tracking) to D1 via canUseD1 probe with automatic KV fallback
- Batch send_logs inserts (recordSendBatch) and add group_id/ts index
- Add storage-prune scheduled task for expired dedup/state/tracking rows
- Add TTL to invite:group:{id} index and audit all ephemeral KV keys
- Add D1 indexes for the new tables
- Sync AGENTS.md, README.md/zh and docs/ (en/zh) with the new storage layout

server/tasks/storage-prune.ts

@@ -0,0 +1,40 @@
+import { cfEnv } from "../lib/cf";
+import { log } from "../lib/lib/log";
+
+const DELIVERY_STATE_RETENTION_MS = 7 * 24 * 3600 * 1000;
+const MESSAGE_TRACKING_RETENTION_MS = 30 * 24 * 3600 * 1000;
+
+/**
+ * Scheduled: purge expired rows from the D1-backed ephemeral stores
+ * (dedup_keys, delivery_state, message_tracking). These replaced the KV keys
+ * that relied on per-entry TTL; D1 rows must be removed by this task instead.
+ */
+export default defineTask({
+  meta: { name: "storage:prune", description: "Prune D1 dedup/delivery/message-tracking rows" },
+  async run(event) {
+    try {
+      const env = cfEnv(event);
+      const now = Date.now();
+      let removed = 0;
+      const dedup = await env.DB.prepare("DELETE FROM dedup_keys WHERE expires_at < ?")
+        .bind(now)
+        .run();
+      removed += dedup.meta?.changes ?? 0;
+      const delivery = await env.DB.prepare("DELETE FROM delivery_state WHERE updated_at < ?")
+        .bind(now - DELIVERY_STATE_RETENTION_MS)
+        .run();
+      removed += delivery.meta?.changes ?? 0;
+      const messages = await env.DB.prepare(
+        "DELETE FROM message_tracking WHERE updated_at < ?",
+      )
+        .bind(now - MESSAGE_TRACKING_RETENTION_MS)
+        .run();
+      removed += messages.meta?.changes ?? 0;
+      if (removed > 0) log.info({ removed }, "Pruned D1 storage rows");
+      return { result: "ok", removed };
+    } catch (err) {
+      log.error({ err }, "Storage prune from cron failed");
+      return { result: "error" };
+    }
+  },
+});