fix(curator): unify under auxiliary.curator (hermes model, dashboard) (#17868)

Voscko reported curator.auxiliary.provider/model was advertised in the
docs but ignored — the review fork read only model.provider/default. The
narrow fix would wire the one-off key through, but that leaves curator
as a parallel system: not in `hermes model` → auxiliary picker, not in
the dashboard Models tab, missing per-task base_url/api_key/timeout/
extra_body.

Unify curator with the rest of the aux task system so `hermes model`
and the dashboard configure it like every other aux task.

Four sources of truth updated:
- hermes_cli/config.py — add 'curator' slot to DEFAULT_CONFIG.auxiliary
  (timeout=600 since reviews run long), drop the one-off curator.auxiliary
  block from DEFAULT_CONFIG.curator.
- hermes_cli/main.py — add ('curator', 'Curator', 'skill-usage review pass')
  to _AUX_TASKS so the CLI picker offers it.
- hermes_cli/web_server.py — add 'curator' to _AUX_TASK_SLOTS so the
  dashboard REST endpoint accepts it.
- web/src/pages/ModelsPage.tsx — add Curator entry so the dashboard
  Models tab renders the task.

agent/curator.py _resolve_review_model() now reads auxiliary.curator
first (canonical), falls back to legacy curator.auxiliary (with an info
log asking users to migrate), then falls back to the main chat model.
Pre-unification users keep working.

Docs updated: docs/user-guide/features/curator.md now points at
`hermes model` → auxiliary → Curator and the dashboard Models tab.

Tests: 6 unit tests on _resolve_review_model (auto default, canonical
slot honored, partial override fallback, legacy fallback with
deprecation log assertion, new-wins-over-legacy, empty-config safety)
plus a cross-registry test that curator is wired into all four sources
of truth. test_aux_tasks_keys_all_exist_in_default_config already
covers the DEFAULT_CONFIG ↔ _AUX_TASKS invariant.

Reported by Voscko on Discord.

hermes_cli/main.py

@@ -1927,6 +1927,7 @@ _AUX_TASKS: list[tuple[str, str, str]] = [
     ("mcp",              "MCP",              "MCP tool reasoning"),
     ("title_generation", "Title generation", "session titles"),
     ("skills_hub",       "Skills hub",       "skills search/install"),
+    ("curator",          "Curator",          "skill-usage review pass"),
 ]