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/session-manager.ts

@@ -30,6 +30,7 @@ import {
   ensureSchema,
   openInboundDb as openInboundDbRaw,
   openOutboundDb as openOutboundDbRaw,
+  openOutboundDbRw as openOutboundDbRwRaw,
   upsertSessionRouting,
   insertMessage,
   migrateMessagesInTable,
@@ -355,6 +356,11 @@ export function openOutboundDb(agentGroupId: string, sessionId: string): Databas
   return openOutboundDbRaw(outboundDbPath(agentGroupId, sessionId));
 }
 
+/** Open the outbound DB for a session with write access. Only safe to call when no container is running. */
+export function openOutboundDbRw(agentGroupId: string, sessionId: string): Database.Database {
+  return openOutboundDbRwRaw(outboundDbPath(agentGroupId, sessionId));
+}
+
 /**
  * Write a message directly to a session's outbound DB so the host delivery
  * loop picks it up. Used by the command gate to send denial responses