initial agent-mgr: app builder platform MVP

Go API server + Preact UI + Claude Code adapter.
- App-centric model (ideas, not repos)
- AgentProvider interface for multi-agent support
- K8s pod lifecycle for sandboxed agent sessions
- Gitea integration (create repos, push branches)
- WebSocket streaming for live session output
- Woodpecker CI/CD pipelines (kaniko build + kubectl deploy)

internal/provider/registry.go

@@ -0,0 +1,31 @@
+package provider
+
+import "fmt"
+
+type Registry struct {
+	providers map[string]AgentProvider
+}
+
+func NewRegistry() *Registry {
+	return &Registry{providers: make(map[string]AgentProvider)}
+}
+
+func (r *Registry) Register(p AgentProvider) {
+	r.providers[p.Info().Name] = p
+}
+
+func (r *Registry) Get(name string) (AgentProvider, error) {
+	p, ok := r.providers[name]
+	if !ok {
+		return nil, fmt.Errorf("provider %q not found", name)
+	}
+	return p, nil
+}
+
+func (r *Registry) List() []Info {
+	infos := make([]Info, 0, len(r.providers))
+	for _, p := range r.providers {
+		infos = append(infos, p.Info())
+	}
+	return infos
+}