feat: implement tool workshop - comprehensive tool system enhancement

- Add Docker Compose and Dockerfile support for tool definitions
- Implement readiness probes with configurable command, timeout, interval
- Create ConfigFolder model for reusable file collections with project overrides
- Add rich tool config fields: port_override, start_command, working_directory, env vars, volumes
- Build unified Tool Workshop UI at /tool-workshop replacing /tool-configs and /tool-types
- Update instance creation to support dockerfile builds, config folder mounting, readiness probes
- Add 3 database migrations for tool_types, tool_configs, and new config_folders table
- Create docker_build.py and readiness_probe.py services
- Add config_folders API with CRUD and project override endpoints

Quality gates: frontend build passes, Python syntax valid, all phases complete

Addresses tool-workshop OpenSpec change

apps/web/src/components/app-shell.tsx

@@ -14,8 +14,7 @@ const NAV_ITEMS: { to: string; label: string; icon: IconName }[] = [
   { to: "/sessions", label: "Sessions", icon: "terminal" },
   { to: "/projects", label: "Projects", icon: "projects" },
   { to: "/ssh-keys", label: "SSH Keys", icon: "profile" },
-  { to: "/tool-types", label: "Tool Types", icon: "code" },
-  { to: "/tool-configs", label: "Tool Configs", icon: "settings" },
+  { to: "/tool-workshop", label: "Tool Workshop", icon: "settings" },
   { to: "/settings", label: "Settings", icon: "settings" }
 ];