feat(gitops): config-as-code via .tinyforge.yml for repo-backed workloads

A dockerfile or static workload can opt in to reading its deploy config from a
.tinyforge.yml in its own repo. Tinyforge fetches the file, shows field-level
drift vs the live config, and an admin applies it with an explicit Sync. The
repo becomes the source of truth for the declared fields. Manual-sync only;
no auto-apply on deploy, no multi-workload reconcile, no create/delete in v1.

Scope is deliberately source-aware and source_config-resident: dockerfile
declares port/healthcheck/deploy_strategy, static declares deploy_strategy.
The file never carries repo coords or secrets (those stay in the encrypted
DB), which keeps credentials out of the repo.

Backend:
- internal/gitops: Spec/ParseSpec (KnownFields rejects unknown keys), a
  source-aware ApplyPlan/BuildPlan, MergeAndValidate (omitted-field-preserving
  deep merge + validate-the-merged-result-then-commit — never a partial
  config), declared-only Drift with normalization, and Fetch with
  ok/no_file/fetch_failed/invalid statuses and token-redacted messages.
- staticsite: DownloadFile added to GitProvider + Gitea/GitHub/GitLab impls,
  reusing each provider's SSRF-safe client; 64 KiB cap; ErrFileNotFound.
- store: 4 additive gitops_* columns + setters (disjoint from UpdateWorkload
  so the edit-form save and a sync never clobber each other).
- api: GET /workloads/{id}/gitops (status + raw + live drift + managed_fields),
  PUT /gitops (admin, enable/path, traversal-safe), POST /gitops/sync (admin,
  per-workload locked read->merge->validate->write, audited to event_log).

Frontend:
- GitOpsPanel.svelte: status pill, a purpose-built field-level drift view,
  .tinyforge.yml preview, enable ToggleSwitch, Sync via ConfirmDialog; all five
  statuses handled, admin affordances gated on the real viewer role.
- GitOps-managed badge (list + detail hero) and a read-only edit-form banner.
- api.ts fetchers + types; i18n apps.detail.gitops.* (en + ru parity).

Built phase-by-phase with an adversarial plan review (caught 5 design flaws
pre-implementation) and an independent review per phase (go / security / ts /
final) — all APPROVE, 0 CRITICAL/HIGH. docs/gitops.md documents the schema and
what's intentionally out of v1. Plan: plans/gitops/.

internal/gitops/apply.go

@@ -0,0 +1,83 @@
+package gitops
+
+// source_config JSON keys this package can overlay. Kept as constants so the
+// apply, merge, and drift paths agree on the exact key strings.
+const (
+	keyPort           = "port"
+	keyHealthcheck    = "healthcheck"
+	keyDeployStrategy = "deploy_strategy"
+)
+
+// Source kinds eligible for GitOps in v1 (git-backed sources only).
+const (
+	SourceDockerfile = "dockerfile"
+	SourceStatic     = "static"
+)
+
+// supportedKeys returns the source_config keys a given source kind accepts
+// from a .tinyforge.yml overlay. A field declared in the file but not in this
+// set is ignored (not applied, not drift-compared) so a shared file can target
+// either source without producing dead keys or false drift.
+//
+// dockerfile: port + healthcheck + deploy_strategy (its real run knobs).
+// static:     deploy_strategy only (a static site has no port/healthcheck).
+func supportedKeys(sourceKind string) map[string]bool {
+	switch sourceKind {
+	case SourceDockerfile:
+		return map[string]bool{keyPort: true, keyHealthcheck: true, keyDeployStrategy: true}
+	case SourceStatic:
+		return map[string]bool{keyDeployStrategy: true}
+	default:
+		return nil
+	}
+}
+
+// IsEligibleSource reports whether GitOps may be enabled for a source kind.
+func IsEligibleSource(sourceKind string) bool {
+	return supportedKeys(sourceKind) != nil
+}
+
+// ApplyPlan is the typed, multi-target plan for applying an overlay. In v1 only
+// SourceConfigPatch is populated; EnvUpserts/Faces are reserved so env (the
+// workload_env table) and faces (the public_faces column) can be added later
+// without reshaping the apply path — they are NOT in v1 (env would re-open the
+// secrets-in-repo hole; faces live in a sibling store).
+type ApplyPlan struct {
+	// SourceConfigPatch holds the source_config keys to overlay onto the live
+	// config. Only keys supported by the target source are present.
+	SourceConfigPatch map[string]any
+
+	// reserved for future phases — see package doc.
+	// EnvUpserts []store.WorkloadEnv
+	// Faces      []plugin.PublicFace
+}
+
+// declaredValues returns the present (non-nil) overlay fields keyed by their
+// source_config JSON key, before the per-source filter. Shared by BuildPlan and
+// Drift so they agree on what the file declared.
+func declaredValues(spec Spec) map[string]any {
+	out := map[string]any{}
+	if spec.Deploy.Port != nil {
+		out[keyPort] = *spec.Deploy.Port
+	}
+	if spec.Deploy.Healthcheck != nil {
+		out[keyHealthcheck] = *spec.Deploy.Healthcheck
+	}
+	if spec.Deploy.DeployStrategy != nil {
+		out[keyDeployStrategy] = *spec.Deploy.DeployStrategy
+	}
+	return out
+}
+
+// BuildPlan maps the present, source-supported overlay fields to a patch for
+// the given source kind. Unsupported/absent fields are dropped.
+func BuildPlan(spec Spec, sourceKind string) ApplyPlan {
+	allowed := supportedKeys(sourceKind)
+	patch := map[string]any{}
+	for k, v := range declaredValues(spec) {
+		if allowed[k] {
+			patch[k] = v
+		}
+	}
+	return ApplyPlan{SourceConfigPatch: patch}
+}