v0.12.0

still_free live set, speed class, and parallel pings.

• still_free pings up to 3 chat models per Lane A host, in parallel
• speed=quality ranks by tier; speed=fast prefers small / flash / lite ids
• 404 skips a dead catalog row instead of stopping at yi-large
• CLI: model-radar still-free --speed fast
• /healthz for live tool list after a unit restart

297 tests.