feat(media): Add comprehensive logging for media uploads - v1.4.1

Implements media upload logging per docs/design/v1.4.1/media-logging-design.md

Changes:
- Add logging to save_media() in starpunk/media.py:
  * INFO: Successful uploads with file details
  * WARNING: Validation/optimization/variant failures
  * ERROR: Unexpected system errors
- Remove duplicate logging in Micropub media endpoint
- Add 5 comprehensive logging tests in TestMediaLogging class
- Bump version to 1.4.1
- Update CHANGELOG.md

All media upload operations now logged for debugging and observability.
Validation errors, optimization failures, and variant generation issues
are tracked at appropriate log levels. Original functionality unchanged.

Test results: 28/28 media tests pass, 5 new logging tests pass

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

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

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.4.1] - 2025-12-16
+
+### Fixed
+
+- Media upload failures are now logged for debugging and observability
+- Validation errors (invalid format, file too large) logged at WARNING level
+- Optimization failures logged at WARNING level
+- Variant generation failures logged at WARNING level (upload continues)
+- Unexpected errors logged at ERROR level with error type and message
+- Successful uploads logged at INFO level with file details
+- Removed duplicate logging in Micropub media endpoint
+
 ## [1.4.0rc1] - 2025-12-16
 
 ### Added