Add community node protocol spec, Agent Skills, and make the failing tests hermetic

Community nodes (Phase 1 of plan.md): the protocol specification in
services/nodes/spec.py as the single source of truth, GET /nodes/spec.json,
a generated protocol docs page, the Community nodes API docs group, and the
implementation plan plus the residential proxy research. The no-open-proxy rule
is enforced in the spec (open_proxy cannot be set).

Agent Skills: register the Skills API docs group, cascade skills on account
deletion, add the nested CLAUDE.md, README and routes docs, and cover the
parser, the fetcher (end to end against a mock origin), the data layer and the
routes with 73 unit and 16 api tests.

Tests made hermetic with the repo's existing patterns instead of ambient
environment: embeddings tests set OPENROUTER_API_KEY via monkeypatch, the
workspace tests install FakeBackend via runtime.set_backend, and the skills
install tests use run_async. DockerCliBackend now returns 127 (command not
found) when the CLI is missing instead of raising FileNotFoundError, so a host
without docker answers with a clean error rather than a 500. The Providers tab
empty state no longer names the Model routes tab.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

docker-compose.yml

@@ -5,7 +5,7 @@ services:
     build:
       context: .
       dockerfile: Dockerfile
-    restart: unless-stopped
+    restart: always
     env_file:
       - .env
     user: "${DEVPLACE_UID:-1000}:${DEVPLACE_GID:-1000}"
@@ -35,7 +35,7 @@ services:
     build:
       context: .
       dockerfile: nginx/Dockerfile
-    restart: unless-stopped
+    restart: always
     ports:
       - "127.0.0.1:${PORT:-10500}:80"
     environment: