feat(db): add oauth_clients table for dynamic client registration

* Introduced oauth_clients table with fields for client_id, client_name, redirect_uris, and created_at.
* Updated agent_persona_parts, agent_persona_skills, agent_persona_guardrails, agent_persona_traits, and arc_stage_parts tables to use unique constraints instead of primary keys for composite indexes.

internal/app/app.go

@@ -100,7 +100,7 @@ func Run(ctx context.Context, configPath string) error {
 		}
 	}
 	authCodes := auth.NewAuthCodeStore()
-	dynClients := auth.NewDynamicClientStore()
+	dynClients := auth.NewPostgresClientStore(db.Pool())
 	activeProjects := session.NewActiveProjects()
 
 	logger.Info("ai providers initialised",
@@ -183,7 +183,7 @@ func Run(ctx context.Context, configPath string) error {
 	}
 }
 
-func routes(logger *slog.Logger, cfg *config.Config, info buildinfo.Info, db *store.DB, embeddings *ai.EmbeddingRunner, metadata *ai.MetadataRunner, bgEmbeddings *ai.EmbeddingRunner, bgMetadata *ai.MetadataRunner, keyring *auth.Keyring, oauthRegistry *auth.OAuthRegistry, tokenStore *auth.TokenStore, authCodes *auth.AuthCodeStore, dynClients *auth.DynamicClientStore, activeProjects *session.ActiveProjects) (http.Handler, error) {
+func routes(logger *slog.Logger, cfg *config.Config, info buildinfo.Info, db *store.DB, embeddings *ai.EmbeddingRunner, metadata *ai.MetadataRunner, bgEmbeddings *ai.EmbeddingRunner, bgMetadata *ai.MetadataRunner, keyring *auth.Keyring, oauthRegistry *auth.OAuthRegistry, tokenStore *auth.TokenStore, authCodes *auth.AuthCodeStore, dynClients auth.ClientStore, activeProjects *session.ActiveProjects) (http.Handler, error) {
 	mux := http.NewServeMux()
 	accessTracker := auth.NewAccessTracker()
 	oauthEnabled := oauthRegistry != nil