feat: GPU-accelerated Whisper API for RTX 2080 (sm_75)

- Pure Rust: Axum 0.7 + whisper-rs 0.13 (CUDA FFI)
- Async job queue with SSE progress streaming
- Webhook delivery with 5x exponential backoff
- Disk-persisted job state (survives restarts)
- Anti-hallucination params: no_speech_thold, entropy_thold, suppress_blank
- CUDA sm_75 flags: GGML_CUDA_FORCE_MMQ, GGML_CUDA_GRAPHS, GGML_CUDA_FA_ALL_QUANTS
- Configurable via env: CUDA_DEVICE, WHISPER_MODEL_PATH, PORT, DATA_DIR
- Gitea Actions CI: build + push to git.sal.giize.com registry
- Multi-stage Dockerfile with customizable CUDA_VERSION ARG

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.gitignore

@@ -0,0 +1,23 @@
+# Rust build artifacts
+/target/
+Cargo.lock
+
+# Runtime data — job state, audio uploads, whisper model
+/data/
+*.gguf
+*.ggml
+*.bin
+
+# Logs
+*.log
+/tmp/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*~
+
+# OS
+.DS_Store
+Thumbs.db