feat(services): builder selection, resource reservations, static builder (C3)

services.builder picks the build strategy per service: auto detects from
repo contents (Dockerfile → railpack → nixpacks), explicit overrides force
a builder, and static builds assets in a node stage then serves them from
an nginx image (static_build_cmd/static_dir, port 80 default).

- cpu_reserve/memory_reserve → Docker CPU shares + MemoryReservation;
  cpu/memory stay hard caps (NanoCPUs/Memory). Empty string clears.
- app_settings.default_cpu/default_memory override service-create
  fallbacks; capacity_policy=block fails deploys whose requested memory
  exceeds node capacity (default warn logs via slog).
- Resource specs are validated — "512mb" fails instead of silently
  dropping the limit.
- Fixes: deployments.go hardcoded nixpacks (auto-detect was dead code);
  DockerfileBuilder passed the Dockerfile *path* as build-context content;
  BuildImage never drained the daemon stream so builds could abort and
  errors went unseen — stream is now consumed and errorDetail surfaced.
- CLI: --builder/--cpu-reserve/--memory-reserve/--static-cmd/--static-dir
  on create+update; MCP args on services create/update; UI Build &
  Resources card; OpenAPI + llms.txt + CLI.md.

Verified live: static build of a real repo → nginx image → deployed;
reserves reach HostConfig (shares=256, MemoryReservation=128Mi);
validation rejects bad specs; builder persists + clears.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

llms.txt

@@ -18,6 +18,7 @@ Base URL: `https://<host>/api/v1`. OpenAPI: `docs/api/openapi.yaml`.
 - **Deployments**: serialized per service — a deploy on a busy service returns `status: queued` and runs when the active one finishes. `POST /deployments/{id}/cancel` drops queued (`200 cancelled`) or aborts running (`202 cancelling`) work. `no_cache: true` on create disables the Docker layer cache. `PUT /services/{id}/variables` accepts `redeploy: true` to apply env changes to running containers.
 - **Volumes**: service mounts via `PUT /services/{id}` `volumes: [{type: volume|bind, source, target, read_only}]` — replaces the whole list (`[]` clears), applied on next deploy. `GET /admin/volumes` inventories node volumes with `in_use` flags; `DELETE /admin/volumes/{name}` removes unused ones (admin).
 - **Domains**: multiple hostnames per service via `GET|POST /services/{id}/domains`, `DELETE /services/{id}/domains/{domain_id}`, `POST …/{domain_id}/default` (mirrors `services.domain`). `GET /services/{id}/domains/check` returns `ok|wrong-target|pending` per domain vs `app_settings.public_ip`/`PUBLIC_IP`. `PUT` `maintenance_mode` redirects all traffic to `GET /maintenance` (needs `base_url`/`BASE_URL` setting); `basic_auth: [{username,password}]` stores bcrypt htpasswd and gates the route — responses return usernames only.
+- **Builders & resources**: service field `builder` = `auto|railpack|nixpacks|dockerfile|static` (auto detects; static builds assets with `static_build_cmd` and serves `static_dir` via nginx:80). `cpu`/`memory` are hard caps; `cpu_reserve`/`memory_reserve` are soft reservations (CPU shares / MemoryReservation) — empty string clears. `app_settings.default_cpu`/`default_memory` set instance defaults; `app_settings.capacity_policy=block` rejects deploys exceeding node memory (default `warn`).
 - **Identifiers**: all ids are UUIDs. Tokens: `cnp_` user PATs, `cagt_` agent onboarding tokens.
 
 ## Core objects