docs(spec): presets record themselves in exdata.meta; job-labels backlog item

- no preset field on the server: the client puts preset name + hash into
  the job's exdata JSON under 'meta', passed through uninterpreted; the
  worker skips 'meta' silently; 'preset report' filters jobs client-side
- drop the local submission log idea
- job-labels: independent backlog item (general server-side labels)
- bug-1970: note the dropped REST 'tags' field

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

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

@@ -572,10 +572,6 @@ Decided 2026-10-12 (user), so a rename never strands jobs:
 - **Open for requirements**:
   - ~~How resource defaults combine with a job's own resreq~~ — settled
     2026-10-09, owned by `job-config-merge`.
-  - Raised 2026-10-12, not yet decided:
-    - Job labels (`--label key=value`, e.g. the preset name) and a summary
-      grouped by label, to compare tuning variants: here,
-      `job-status-detail-display`, or `xcecli-presets`?
   - Settled 2026-10-12: scheduling and execution values frozen at
     dispatch, re-read on requeue ("Dispatch record"); a removed profile
     makes its jobs pend ("Profile removed while jobs use it"); clean env for
@@ -586,7 +582,9 @@ Decided 2026-10-12 (user), so a rename never strands jobs:
     split into `job-sandbox-execution`; v1 attributes are the four plus the
     job starter, others ship with their job features; profile history and
     change audit deferred to the roadmap (`config-history-audit`): the
-    content hash and the dispatch record already show what each run used.
+    content hash and the dispatch record already show what each run used;
+    no job labels needed here (presets record themselves in `exdata.meta`;
+    general labels are the `job-labels` backlog item).
 - **Out**:
   - The `sandbox` mode and its options, I/O directories, capability
     advertisement, placement by mode and the worker sandbox mechanics