api+ui: kind-scoped save/delete endpoints and links

API: /config/{services,jobs,tools,static}/{name} now pin the twin they
target — _save_deployment/_delete_deployment take an explicit kind so a
patch to a 'backup' service can't bleed into a 'backup' job/tool. Add
/tools and /static endpoints; keep /deployments/{name} kind-agnostic.
New test_kind_twins proves per-kind save/delete isolation on disk.

UI: ConfigPanel and CreateDeploymentForm write to the kind-scoped
resource; GatewayPanel/NodeDetail/DeploymentsSection link via a shared
detailPath(name, kind) helper instead of the ambiguous /deployment/:name.

Includes incidental ruff-format reflow of untouched api files.

app/src/components/detail/SystemdPanel.tsx

@@ -27,6 +27,14 @@ export function SystemdPanel({ name, systemd }: SystemdPanelProps) {
       <div className="grid grid-cols-2 gap-x-6 gap-y-2 text-sm mt-3">
         <span className="text-[var(--muted)]">Unit</span>
         <span className="font-mono break-all">{systemd.unit_name}</span>
+        {systemd.timer && (
+          <>
+            <span className="text-[var(--muted)]">Timer unit</span>
+            <span className="font-mono break-all">
+              {systemd.unit_name.replace(".service", ".timer")}
+            </span>
+          </>
+        )}
         <span className="text-[var(--muted)]">Path</span>
         <span className="font-mono break-all">{systemd.unit_path}</span>
         {systemd.timer && (