Tools as PATH deployments; demote behavior from lifecycle logic

- manifest: RunPath (runner: path) — a CLI on PATH via `uv tool install`, manager
  = path, no unit/route (like remote/static).
- lifecycle/service: a path deployment's start/stop = install/uninstall (routed
  through activate/deactivate, which skip the reinstall when already on PATH).
  `castle service start/stop <tool>` and status now dispatch by manager; status
  shows the manager tag [systemd|caddy|path|none].
- config.tools() now derives from `runner: path` services, not the behavior label.
- castle-api: the "installed" flag derives from manager==path, not behavior==tool.
- create: a python-cli stack emits a `runner: path` service.

`behavior` no longer drives any runtime logic — it survives only as a display
label + `list --behavior` filter. Verified live: html2text uninstall→reinstall
round-trip via `castle service stop/start`.

core/src/castle_core/config.py

@@ -139,8 +139,12 @@ class CastleConfig:
 
     @property
     def tools(self) -> dict[str, ProgramSpec]:
-        """Return programs that are tools (behavior == 'tool')."""
-        return {k: v for k, v in self.programs.items() if v.behavior == "tool"}
+        """Programs deployed as a PATH tool (a `runner: path` service) — derived
+        from deployments, not the `behavior` label."""
+        tool_programs = {
+            s.program or n for n, s in self.services.items() if s.run.runner == "path"
+        }
+        return {k: v for k, v in self.programs.items() if k in tool_programs}
 
     @property
     def frontends(self) -> dict[str, ProgramSpec]: