chore(ops): restart:unless-stopped so the stack survives host reboots

The Pi stack stayed down after a reboot (services had no restart policy). Add
restart:unless-stopped to postgres/backup/api/frontend (not the init-keys one-shot).
Also commits todo.md (running follow-ups: drafts fetch, live OAuth/subdomain, sent re-sync).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -1,5 +1,6 @@
 services:
   postgres:
+    restart: unless-stopped
     # pgvector-enabled Postgres 16 (semantic search). Drop-in for postgres:16 data;
     # the 'vector' extension is created by the AddEmbeddingColumn migration.
     image: pgvector/pgvector:pg16
@@ -27,6 +28,7 @@ services:
   # encrypted disk and be included in your off-machine backup regime (see SECURITY.md).
   # Restore: docker compose exec -T postgres psql -U inboxintel -d inboxintel < backups/<file>.sql
   backup:
+    restart: unless-stopped
     image: pgvector/pgvector:pg16
     entrypoint: /bin/sh
     command:
@@ -64,6 +66,7 @@ services:
       - keys:/keys
 
   api:
+    restart: unless-stopped
     build:
       context: .
       dockerfile: src/InboxIntel.Api/Dockerfile
@@ -98,6 +101,7 @@ services:
       - "127.0.0.1:8080:8080"
 
   frontend:
+    restart: unless-stopped
     build:
       context: ./frontend
       dockerfile: Dockerfile