v2 phase 5: scheduling fixes, media handling, command processing

- Host sweep: fix DELETE journal mode, busy_timeout, seq in recurrence INSERT
- Outbound files: delivery reads from outbox dir, passes buffers to adapter,
  cleans up after delivery. Chat SDK bridge sends files via postMessage.
- Inbound attachments: formatter includes attachment info in prompts
- Commands: categorize /commands as admin, filtered, or passthrough.
  Admin commands check sender against NANOCLAW_ADMIN_USER_ID.
  Filtered commands silently dropped. Passthrough sent raw to agent.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/channels/adapter.ts

@@ -34,10 +34,17 @@ export interface InboundMessage {
   timestamp: string;
 }
 
+/** A file attachment to deliver alongside a message. */
+export interface OutboundFile {
+  filename: string;
+  data: Buffer;
+}
+
 /** Outbound message from host to adapter. */
 export interface OutboundMessage {
   kind: string;
   content: unknown; // parsed JSON from messages_out
+  files?: OutboundFile[]; // file attachments from the session outbox
 }
 
 /** Discovered conversation info (from syncConversations). */