PR-06: File Delivery Reliability (Mobile Reachability)

[Alimedhat000]

Summary

Make file downloads reliable and mobile-accessible.

Changes Needed

1. Add GET /api/files//download endpoint (binary stream)
2. Keep GET /api/files/ but return API download URL
3. Never return internal-only hostnames (minio:9000) to clients

Acceptance Criteria

• Mobile can fetch files using only app base URL
• Large files stream without loading full content in memory
• No internal hostname leakage