fix: fail closed on unusable Codex auth during sandbox auth merge

When reusing a Codex sandbox, the workspace-restore step now performs
an auth-merge check before adopting the sandbox's auth.json. The merge
fails closed when:

- host or sandbox Codex auth is unusable (missing token or account)
- the subscription payload shapes differ between host and sandbox
- subscription account identities do not match

Additional hardening: node absence on PATH during the embedded decision
script now exits non-zero instead of silently falling through. Co-change
comments link parseAuth (the embedded script) to hasUsableAuthPayload
(codex-home.ts) so a future auth-format change cannot silently diverge
between the two implementations.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

docker/docker-compose.yml

@@ -0,0 +1,40 @@
+services:
+  db:
+    image: postgres:17-alpine
+    environment:
+      POSTGRES_USER: paperclip
+      POSTGRES_PASSWORD: paperclip
+      POSTGRES_DB: paperclip
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U paperclip -d paperclip"]
+      interval: 2s
+      timeout: 5s
+      retries: 30
+    ports:
+      - "5432:5432"
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+
+  server:
+    build:
+      context: ..
+      dockerfile: Dockerfile
+    ports:
+      - "3100:3100"
+    environment:
+      DATABASE_URL: postgres://paperclip:paperclip@db:5432/paperclip
+      PORT: "3100"
+      SERVE_UI: "true"
+      PAPERCLIP_DEPLOYMENT_MODE: "authenticated"
+      PAPERCLIP_DEPLOYMENT_EXPOSURE: "private"
+      PAPERCLIP_PUBLIC_URL: "${PAPERCLIP_PUBLIC_URL:-http://localhost:3100}"
+      BETTER_AUTH_SECRET: "${BETTER_AUTH_SECRET:?BETTER_AUTH_SECRET must be set}"
+    volumes:
+      - paperclip-data:/paperclip
+    depends_on:
+      db:
+        condition: service_healthy
+
+volumes:
+  pgdata:
+  paperclip-data: