Configure S3/R2 file storage for photo uploads

[robert197]

Description

Set up cloud file storage for inspection photos using django-storages.

Requirements

• django-storages with S3-compatible backend (works with AWS S3 and Cloudflare R2)
• Separate storage backends:
  • MediaStorage for user uploads (photos)
  • StaticStorage for static files (optional, can use default)
• Automatic thumbnail generation on upload (Pillow)
  • Thumbnail size: 300x300 max, maintaining aspect ratio
• Signed URLs for private photo access (24h expiry)
• Local file storage fallback for development (MEDIA_ROOT)
• Upload size limit: 10MB per photo
• Accepted formats: JPEG, PNG, HEIC (convert HEIC to JPEG on upload)

Configuration

# settings/base.py
STORAGES = {
    "default": {"BACKEND": "storages.backends.s3boto3.S3Boto3Storage"},
    "staticfiles": {"BACKEND": "django.contrib.staticfiles.storage.StaticFilesStorage"},
}

Acceptance Criteria

• Photos upload to S3/R2 in production
• Local dev uses filesystem storage
• Thumbnails auto-generated on upload
• Signed URLs work with configurable expiry
• HEIC to JPEG conversion works

[robert197]

Dependencies: Blocked by #7, #3. See build order in #44.