fix(host-sweep): reopen outbound DB as writable for orphan claim cleanup

PR #2151 added deleteOrphanProcessingClaims() to resetStuckProcessingRows(),
but outDb is always opened readonly (openOutboundDb uses immutable: true).
The write silently failed, leaving orphan processing_ack rows that block
future message delivery for the session.

Fix: add openOutboundDbRw() alongside the existing readonly opener and use
it in resetStuckProcessingRows() to open a short-lived writable handle just
for the delete. The readonly handle is still used for all reads above.

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

src/db/session-db.ts

@@ -32,6 +32,14 @@ export function openOutboundDb(dbPath: string): Database.Database {
   return db;
 }
 
+/** Open the outbound DB for a session with write access. Only safe to call when no container is running. */
+export function openOutboundDbRw(dbPath: string): Database.Database {
+  const db = new Database(dbPath);
+  db.pragma('journal_mode = DELETE');
+  db.pragma('busy_timeout = 5000');
+  return db;
+}
+
 export function upsertSessionRouting(
   db: Database.Database,
   routing: { channel_type: string | null; platform_id: string | null; thread_id: string | null },