docs(spec): application-profile params and annotations; 0-valued rusage dropped; app-submit-hook backlog

- params: declared application settings XCE carries but never interprets;
  exported as XCE_APP_PARAM_*; job overrides with --app-param; undeclared
  names rejected; stored in exdata app_params
- annotations: metadata for tools, also exported as XCE_APP_ANN_* (name
  conversion, collision check, size limits, no secrets)
- merge drops 0-valued rusage terms so the scheduler sees no term (today a
  0 term still rejects hosts where the resource is over-committed)
- app-submit-hook (esub-style) recorded as a roadmap backlog item only

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

.kiro/specs/xcecli-presets/brief.md

@@ -15,7 +15,7 @@ configuration level.
 
 ## Desired Outcome
 - **A preset is a set of job options** (`--app`, `--queue`, `-R`, `-n`,
-  env, limits, ...), named and stored by the client. `xcecli jobs submit
+  env, limits, `--app-param`, ...), named and stored by the client. `xcecli jobs submit
   --preset <name>` expands it; any command-line flag replaces the preset's
   value for that option as a whole (no resreq parsing). The submit carries
   only the expanded values.