feat(sat): fan ceiling check + topology fan tiles

Repurpose the previously-unwired RunFanStressTest into RunFanCheck, a
Load-tier SAT test that drives stressapptest (CPU+memory) and, when a GPU
is present, a GPU burn to 100% simultaneously, then watches every fan
until none has climbed for ~60s. The observed peak RPM per fan is the
"ceiling"; it is persisted through the existing fan-observation store.

MSI G4201 / AMI MegaRAC exposes no host-side fan force (every OEM IPMI
command returns 0xc1; Redfish Thermal is GET-only), so load-driven ramp
is the closest safe equivalent. See
bible-local/decisions/2026-09-04-fan-ceiling-check.md.

- platform.ResolveFanMaxRPM: per-fan max with fallback (persisted peak ->
  peer peak -> current RPM), resolved in platform, not the view.
- platform.ErrTestNotApplicable: no load source or no fan sensors ->
  task lands as cancelled ("not applicable"), never failed, so an
  engineer never sees a false red. executeTaskWithOptions maps the
  sentinel; finalizeTaskForResult honours a pre-set TaskCancelled.
- Verdict FAIL only for a fan at 0 RPM / IPMI cr-nr under load.
- /topo: one small spinning square per fan, sized by RPM / resolved max,
  clickable through to a new "fan" component-detail type; per-fan status
  recorded to the component-status DB from the fan SAT summary.
- Wiring: /api/sat/fan/run route, "fan" task target, Load-page card,
  stress-mode Run All.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VHG21rgTUiR1G3qFHTVmN

bible-local/architecture/api-surface.md

@@ -53,6 +53,7 @@ All SAT run endpoints enqueue an async task. Response: `{"task_id": "..."}`.
 | POST   | `/api/sat/memory-stress/run`               | Memory stress                     |
 | POST   | `/api/sat/sat-stress/run`                  | Combined storage+memory stress    |
 | POST   | `/api/sat/platform-stress/run`             | Fan + thermal stress              |
+| POST   | `/api/sat/fan/run`                         | Fan ceiling check (CPU+GPU load until fans plateau; Load tier). Not-applicable → task cancelled, not failed. |
 | POST   | `/api/sat/run-all`                          | Plan + enqueue the whole validate/check set server-side. Body: `{stress_mode, amd_targets[], nvidia_gpu_indices[]}` (operator intent only). Response: `{task_ids[], task_count, notes[]}`. Hardware presence/readiness and which tasks to run are decided by `handler.planSATRunAll`, not the page. |
 | GET    | `/api/sat/stream`                          | SSE: live SAT log stream          |
 | POST   | `/api/sat/abort`                           | Abort the running SAT task        |