v0.9.0 — GPU support, configurable data dirs, rename ollama models

New:
- GPU_NVIDIA=1: separate ollama-gpu instance with nvidia runtime
- 5 GPU models sized for 3060 12GB with per-model num_gpu control
- flash attention + q8_0 KV cache for VRAM efficiency
- DATA_DIR / DATA_DIR_<SERVICE> env vars for relocating data directories
- GPU integration tests (registration, chat, uncensored, vision)

Changed:
- all model names: local-ollama-* → ollama-cpu-*, GPU uses ollama-gpu-*
- moondream replaced with gemma3:4b (working vision model)
- all .data/ volume mounts parameterized via env vars
- tests, README, fallbacks updated for new naming