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>

app/backend/internal/build/manager.go

@@ -16,6 +16,7 @@ type BuildManager struct {
 	railpackBuilder   *RailpackBuilder
 	nixpacksBuilder   *NixpacksBuilder
 	dockerfileBuilder *DockerfileBuilder
+	staticBuilder     *StaticBuilder
 	dockerClient      *docker.Client
 	cacheManager      *CacheManager
 	parallelBuilder   *ParallelBuilder
@@ -28,6 +29,7 @@ const (
 	BuildTypeRailpack   BuildType = "railpack"
 	BuildTypeNixpacks   BuildType = "nixpacks"
 	BuildTypeDockerfile BuildType = "dockerfile"
+	BuildTypeStatic     BuildType = "static"
 	BuildTypePrebuilt   BuildType = "prebuilt"
 )
 
@@ -39,6 +41,7 @@ func NewBuildManager(workDir string, dockerClient *docker.Client) *BuildManager
 		railpackBuilder:   NewRailpackBuilder(workDir, dockerClient),
 		nixpacksBuilder:   NewNixpacksBuilder(workDir, dockerClient),
 		dockerfileBuilder: NewDockerfileBuilder(workDir, dockerClient),
+		staticBuilder:     NewStaticBuilder(dockerClient),
 		dockerClient:      dockerClient,
 		cacheManager:      cacheManager,
 		parallelBuilder:   parallelBuilder,
@@ -80,6 +83,8 @@ func (bm *BuildManager) Build(ctx context.Context, req *types.BuildRequest) (*ty
 		return bm.nixpacksBuilder.Build(ctx, req)
 	case BuildTypeDockerfile:
 		return bm.dockerfileBuilder.Build(ctx, req)
+	case BuildTypeStatic:
+		return bm.staticBuilder.Build(ctx, req)
 	case BuildTypePrebuilt:
 		return bm.buildPrebuilt(ctx, req)
 	default: