fix: import spaces before everything else, per HF docs

fix: wire GPU placeholder into Blocks graph so ZeroGPU detector finds it

fix: add placeholder @spaces.GPU function required by ZeroGPU

fix: unpin pydantic to resolve gradio dependency conflict

fix: remove gradio pin, platform provides it via sdk_version

fix: pin torch to ZeroGPU-compatible version

Clean deploy: numpy vector search, binaries excluded