M3a: meetrec-server storage service + automatic upload from the app

- server/meetrec-server: FastAPI storage API (upload bundle with wav/
  txt/srt/json + metadata incl. agenda, list, fetch, download, delete);
  file-based index.json, no database; Docker Compose on port 8090,
  Tailscale-only bind like whisper-server; Ollama env prepared for M3c
  (gemma4:12b, German)
- phone: StorageClient (stdlib multipart upload); RecorderService uploads
  the bundle in the background after the final pass and publishes
  UploadState (Uploading/Done/Error) to the UI
- app: Library URL setting (persisted, default http://100.103.83.12:8090,
  empty disables upload); status line reports upload progress
- storage API validated locally end-to-end: upload, list, metadata,
  download, path-traversal rejected, delete

server/meetrec-server/Dockerfile

@@ -0,0 +1,11 @@
+FROM python:3.12-slim
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY main.py .
+
+ENV MEETREC_DATA=/data
+EXPOSE 8090
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8090"]