feat(cli): add --disable-snapshot-compaction to skip JPEG→MP4 worker

[rhodium-inc]

Summary

Add an opt-in --disable-snapshot-compaction CLI flag (and matching disableSnapshotCompaction settings field) that skips the background JPEG→MP4 snapshot compaction worker.

Motivation

The snapshot compaction worker compresses older JPEG frames into H.265 MP4 chunks every 5 minutes (great for users browsing the MP4 timeline UI, ~10-30x size reduction).

However, for tools that only consume accessibility_text and ui_events (task-mining tools, automation, headless analysis pipelines), the worker is pure overhead:

• ffmpeg H.265 encoding visibly bumps CPU usage every 5 minutes
• The generated MP4s are never read
• Disk savings can be achieved via --retention-days instead

--disable-vision already exists but is too coarse — it also skips OCR / accessibility capture, which we still need.

Behavior

• Default: false — no change for existing users
• When set:
  • start_snapshot_compaction is not called
  • Startup log prints: snapshot compaction disabled via --disable-snapshot-compaction
  • Individual JPEGs persist until --retention-days cleans them up

Implementation

• `screenpipe-config`: `RecordingSettings.disable_snapshot_compaction` (persisted to settings.json via `disableSnapshotCompaction`)
• `screenpipe-engine/cli`: `--disable-snapshot-compaction` flag on `record` subcommand
• `screenpipe-engine/recording_config`: `RecordingConfig` propagation
• `screenpipe-engine/bin`: gate `start_snapshot_compaction()` call

Validation

• `cargo build --release --target x86_64-pc-windows-msvc --workspace --exclude screenpipe-rfdetr-mlx` passes on Windows (rebased onto current main, includes [codex] fix Windows ONNX Runtime version #3370)
• `screenpipe record --help` shows the new flag
• 15-minute run with `--disable-snapshot-compaction --disable-audio` confirmed:
  • No `snapshot compaction worker started` log line
  • No MP4 files produced
  • JPEGs accumulate as expected (cleaned later by retention)

Context

This is the first of a few small CLI flags we're adding for task-mining / headless-recording use cases. Submitted as a small, isolated PR to keep review easy.