feat: v1.4.0 Phase 5 - Testing & Documentation

Complete Phase 5 of v1.4.0 "Media" release with comprehensive release
preparation.

CHANGELOG Updates:
- Added v1.4.0rc1 section with comprehensive release notes
- Documented all four phases:
  * Large Image Support (50MB limit, tiered resize)
  * Image Variants (thumb, small, medium, large)
  * Micropub Media Endpoint (W3C compliant)
  * Enhanced Feed Media (Media RSS, JSON Feed extension)
- Standards compliance documented (W3C Micropub, Media RSS 2.0)
- Storage impact and backwards compatibility notes
- Configuration options (STARPUNK_ABOUT_URL)

Version Bump:
- Updated starpunk/__init__.py to 1.4.0rc1
- Version info tuple includes rc1 designator

Implementation Report:
- Created docs/design/v1.4.0/2025-12-16-v140-implementation-complete.md
- Complete summary of all five phases
- Test results: 850 passing, 19 failing
- Known issues documented (flaky tests, feed cache)
- Acceptance criteria checklist
- Deployment and rollback procedures
- Release recommendation: Ready for RC testing

Test Results:
- Full test suite executed: 850 passed, 19 failed (98% pass rate)
- Core v1.4.0 functionality verified working
- Failures in known flaky tests and unrelated areas
- 5 minutes 58 seconds execution time

Release Status:
- All five phases complete
- Ready for release candidate testing
- Manual verification recommended before final release

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,142 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.4.0rc1] - 2025-12-16
+
+### Added
+
+- **Large Image Support** - Accept and optimize images up to 50MB (Phase 1)
+  - Increased file size limit from 10MB to 50MB for image uploads
+  - Tiered resize strategy based on input size:
+    - <=10MB: 2048px max dimension, 95% quality
+    - 10-25MB: 1600px max dimension, 90% quality
+    - 25-50MB: 1280px max dimension, 85% quality
+  - Iterative quality reduction if output still >10MB after optimization
+  - Rejects if optimization cannot achieve <=10MB target (minimum 640px at 70% quality)
+  - Animated GIF detection with 10MB size limit (cannot be resized)
+  - All optimized images kept at or under 10MB for web performance
+
+- **Image Variants** - Multiple image sizes for responsive delivery (Phase 2)
+  - Four variants generated automatically on upload:
+    - thumb: 150x150 center crop for thumbnails
+    - small: 320px width for mobile/low bandwidth
+    - medium: 640px width for standard display
+    - large: 1280px width for high-res display
+    - original: As uploaded (optimized, <=2048px)
+  - Variants stored in date-organized folders (data/media/YYYY/MM/)
+  - Database tracking in new `media_variants` table
+  - Synchronous/eager generation on upload
+  - Only new uploads get variants (existing media unchanged)
+  - Cascade deletion with parent media
+  - Variants included in `get_note_media()` response (backwards compatible)
+
+- **Micropub Media Endpoint** - W3C-compliant media upload (Phase 3)
+  - New POST `/micropub/media` endpoint for file uploads
+  - Multipart/form-data with single file part named 'file'
+  - Bearer token authentication with `create` scope (no new scope needed)
+  - Returns 201 Created with Location header on success
+  - Automatic variant generation on upload
+  - OAuth 2.0 error format for all error responses
+  - Media endpoint advertised in `q=config` query response
+  - Photo property support in Micropub create requests:
+    - Simple URL strings: `"photo": ["https://example.com/image.jpg"]`
+    - Structured with alt text: `"photo": [{"value": "url", "alt": "description"}]`
+    - Multiple photos supported (max 4 per ADR-057)
+    - External URLs logged and ignored (no download)
+    - Photo captions preserved from alt text
+
+- **Enhanced Feed Media** - Full Media RSS and JSON Feed variants (Phase 4)
+  - RSS 2.0: Complete Media RSS namespace support
+    - `media:group` element for multiple sizes of same image
+    - `media:content` for each variant with dimensions and file size
+    - `media:thumbnail` element for preview images
+    - `media:title` for captions (when present)
+    - `isDefault` attribute on largest available variant
+  - JSON Feed 1.1: `_starpunk` extension with variants
+    - All variants with URLs, dimensions, and sizes
+    - Configurable `about` URL for extension documentation
+    - Default: `https://github.com/yourusername/starpunk`
+    - Override via `STARPUNK_ABOUT_URL` config
+  - ATOM 1.0: Enclosures with title attribute for captions
+  - Backwards compatible: Feeds work with and without variants
+
+### Changed
+
+- **Image Optimization** - Enhanced for large file handling
+  - `optimize_image()` now accepts `original_size` parameter
+  - Returns both optimized image and bytes (avoids re-saving)
+  - Iterative quality reduction loop for difficult-to-compress images
+  - Safety check prevents infinite loops (minimum 640px dimension)
+
+- **Media Storage** - Extended with variant support
+  - `save_media()` generates variants synchronously after saving original
+  - Variants cleaned up automatically on generation failure
+  - Database records original as 'original' variant type
+  - File size passed efficiently without redundant I/O
+
+### Technical Details
+
+- **Migration 009**: Add `media_variants` table
+  - Tracks variant_type, path, dimensions, and file size
+  - Foreign key to media table with cascade delete
+  - Unique constraint on (media_id, variant_type)
+  - Index on media_id for efficient lookups
+
+- **New Functions**:
+  - `get_optimization_params(file_size)` - Tiered resize strategy
+  - `generate_variant()` - Single variant generation
+  - `generate_all_variants()` - Full variant set with DB storage
+  - `extract_photos()` - Micropub photo property parsing
+  - `_attach_photos_to_note()` - Photo attachment to notes
+
+- **Modified Functions**:
+  - `validate_image()` - 50MB limit, animated GIF detection
+  - `optimize_image()` - Size-aware tiered optimization
+  - `save_media()` - Variant generation integration
+  - `get_note_media()` - Includes variants (when present)
+  - `handle_query()` - Advertises media-endpoint in config
+  - `handle_create()` - Photo property extraction and attachment
+  - `generate_rss_streaming()` - Media RSS support
+  - `_build_item_object()` - JSON Feed variants
+  - `generate_atom_streaming()` - Enclosure title attributes
+
+- **Configuration Options**:
+  - `STARPUNK_ABOUT_URL` - JSON Feed extension documentation URL
+
+### Standards Compliance
+
+- W3C Micropub Media Endpoint Specification
+- Media RSS 2.0 Specification (RSS Board)
+- JSON Feed 1.1 with custom extension
+- OAuth 2.0 Bearer Token Authentication
+- RFC 3339 date formats in feeds
+
+### Storage Impact
+
+- Variants use approximately 4x storage per image:
+  - Original: 100%
+  - Large (1280px): ~50%
+  - Medium (640px): ~25%
+  - Small (320px): ~12%
+  - Thumb (150x150): ~3%
+- Typical 500KB optimized image → ~900KB total with variants
+- Only new uploads generate variants (existing media unchanged)
+
+### Backwards Compatibility
+
+- Existing media files work unchanged
+- No variants generated for pre-v1.4.0 uploads
+- Feeds handle media with and without variants gracefully
+- `get_note_media()` only includes 'variants' key when variants exist
+- All existing Micropub clients continue to work
+
+### Related Documentation
+
+- ADR-057: Media Attachment Model
+- ADR-058: Image Optimization Strategy
+- ADR-059: Full Feed Media Standardization
+- Design: `/docs/design/v1.4.0/media-implementation-design.md`
+
 ## [1.3.1] - 2025-12-10
 
 ### Added