feat: implement Phase 11 — inline photo viewing with ratatui-image
Add feature-gated (`images`) inline photo support:
- New types: MediaInfo, PhotoInfo, PhotoDownloadState, ImagesConfig
- Media module: ImageCache (LRU filesystem cache), ImageRenderer (terminal protocol detection)
- Photo metadata extraction from TDLib MessagePhoto with download_file() API
- ViewImage command (v/м) to toggle photo expand/collapse in message selection
- Two-pass UI rendering: placeholder lines in message bubbles + StatefulImage overlay
- Collapse all expanded photos on Esc (exit selection mode)
Dependencies: ratatui-image 8.1, image 0.25 (optional, behind `images` feature flag)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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