feat: deployment-scoped requires + UI editors, gateway nav, services filter

Model:
- Drop `requires` from ProgramSpec; requires is now deployment-only.
  Collapse Requirement to {ref, bind} with kind defaulting to "deployment"
  (drop the unused `version`). System-package preconditions stay on the
  program as `system_dependencies`, synthesized into {kind: system} for the
  functional check. relations.py/deploy.py read only the deployment's requires.
- create.py seeds a stack's substrate dependency onto the deployment, not the
  program. Docs + tests updated.

UI:
- Add a `requires` editor (useRequires) on service, job, and static detail
  pages — edit service→service deps (ref + optional bind env var).
- Restore the gateway route table "Open" column: a kind-aware in-app link to
  each route's deployment.
- Reformat the reach control: name baked into each option
  (localhost:PORT (local) / <name>.<domain> (internal) / <name>.<pubdomain> (public)).
- Services page: sort statics in with systemd services by name, add a
  search + kind-filter bar mirroring the programs page.

cli/tests/test_create.py

@@ -105,12 +105,13 @@ class TestCreateCommand:
         comp = config.programs["guestbook"]
         assert comp.stack == "supabase"
         assert comp.build is not None and comp.build.outputs == ["public"]
-        # The supabase stack seeds a `requires` on the substrate so the graph shows
-        # the dependency (stack stays uncoupled — it just declares the edge once).
-        assert [(r.kind, r.ref) for r in comp.requires] == [("deployment", "supabase")]
         dep = config.statics["guestbook"]
         assert dep.manager == "caddy"
         assert dep.root == "public"
+        # The supabase stack seeds a `requires` on the substrate (on the deployment)
+        # so the graph shows the dependency (stack stays uncoupled — it just declares
+        # the edge once).
+        assert [(r.kind, r.ref) for r in dep.requires] == [("deployment", "supabase")]
         assert config.deployments_of("guestbook") == [("guestbook", "static")]
 
     def test_create_duplicate_fails(self, castle_root: Path, capsys: object) -> None: