v0.26.0:0 - disk-driven model menu (scan sparks; recipes; needs-setup)

The dashboard menu is now the set of models actually downloaded on the
Sparks, not a hard-coded catalog. models.yaml + overrides are reframed as
launch recipes matched to an on-disk model by repo; an on-disk model with
no recipe is flagged needs_setup and its launch settings are inferred from
its config.json for a one-time operator confirmation (discovery.py).

- delete now removes weights AND the menu card (delete_from_disk sweeps all
  hosts; the delete endpoint resolves keys via the live menu)
- new GET /api/models/suggest; /api/models returns the menu + a recipes list
  (download autocomplete); GET /api/models/disk-status removed
- dropped the two legacy Qwen recipes (235B FP8, 2.5 72B)
- tests: +test_discovery.py (cache parsing, infer_recipe, build_menu merge)

HANDOFF.md

@@ -92,7 +92,7 @@ Now that hosts are configured, Show Public Key will give you the paste-ready ins
 From the Spark Control service page, click the Web UI button. You should see:
 
 - A **top status bar** with the currently loaded LLM (or "no model loaded" if Spark 1's vLLM container is fresh).
-- An **LLM tab** with cards for each model in the bundled catalog. Models you've downloaded show "on disk" badges; others show "not downloaded".
+- An **LLM tab** whose cards are the models actually downloaded on your Sparks (the dashboard scans them on load). A model Spark Control doesn't yet know how to launch shows a "needs setup" card; the first switch reads its files, proposes settings, and asks you to confirm once. Use **+ Download a new model** to fetch one — it appears here when it finishes.
 - An **Audio / Speech tab** with health status and Install / Start / Stop / Restart buttons for Parakeet and Kokoro.
 
 If the dashboard loads and both Spark hardware cards show CPU/RAM/GPU stats, **you're in**.