Root cause: FileReader.readAsDataURL() loads the entire file into memory
as a base64 string. With 50+ iPhone photos (3-12 MB each), this exceeds
iOS Safari's per-tab memory limit and freezes the tab.
Changes:
- Replace readAsDataURL with URL.createObjectURL(file) — zero-copy file
reference, no memory bloat (static/index.html)
- Reduce batch size from 4 to 2 — gentler on memory-constrained devices
- Add URL.revokeObjectURL() on reset — prevent blob URL leaks
- Add HEIC/HEIF support to server.py — iPhone format compatibility
Closes#1