docs(spec): xcecli-presets: server preset directory, pull name collisions, /xce/v1 routes

- server presets live in <TopDir>/config/presets/ (or presets.dir in
  app.yaml), one file per preset, re-read on change; not in ClusterConfig
- pull refuses a name collision unless it updates the same server preset;
  --as / --force (keeps .bak); submit uses local presets only
- fix route prefix: /xce/v1/presets, not /api/v1

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.kiro/specs/application-profile/brief.md

@@ -380,7 +380,7 @@ Not part of this spec, recorded here because they replace profile defaults:
   values.
 - Personal presets live one file per preset under `~/.config/xce/presets/`.
 - The apiserver **only shares**: admin-deployed preset files served
-  read-only (`GET /api/v1/presets`, `GET /api/v1/presets/{name}`). Pulling
+  read-only (`GET /xce/v1/presets`, `GET /xce/v1/presets/{name}`) from `<TopDir>/config/presets/`. Pulling
   copies a preset into the local file, so a server preset being removed
   never affects users. `preset diff` / `pull --force` are user-initiated.
 - User-to-user sharing by `preset export` / `import` (file, mail, git).