feat: phase 3 — framebuffer, raw decoder, session pump, snapshot
framebuffer.rs:
- Framebuffer struct (8bpp RGB332, row-major)
- apply_raw() blit, copy_rect() with overlap-safe logic
- to_rgba() via compile-time RGB332 LUT
session.rs:
- ActiveSession: connect + SetEncodings + initial FBUpdateRequest
- Full server message dispatch loop (all 15 message types)
- Raw (encoding 0) and CopyRect (encoding 1) decoders
- Ping response, bandwidth probe bookends, mode change resize
examples/snapshot.rs:
- Connects, waits for first FramebufferUpdate, saves PNG
- Tested against real OmniView at 10.3.0.130:443
- Successfully captured 640x480 frame
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>