feat: add bounded HandBrake video adapter

[szmyty]

Summary

• integrate adapter.media.handbrake and tool.handbrake for video.transcode.whole_file
• expose typed official presets plus side-effect-free planning and CLI execution
• run HandBrakeCLI through renderflow.process/v1 with direct argv, timeout, bounded output, process-tree cancellation, progress heartbeats, and denied network intent
• validate and atomically publish MP4 output with size bounds, SHA-256 provenance, provider/tool evidence, and a flow.artifact/v1 projection
• make the Aniflow ownership boundary explicit for segmentation, boundary selection, manifest ordering, and reconstruction
• publish capability/transform schemas and user/provider documentation

Verification

• formatted all changed Rust sources with rustfmt
• cargo check --workspace --all-targets --locked
• cargo clippy --workspace --lib --bins --all-features --locked -- -D warnings -A clippy::too_many_arguments (allows one inherited warning in the existing build command)
• parsed all checked-in JSON schemas with jq
• exercised capability and adapter-catalog CLI projections
• exercised planning and the complete bounded execution/provenance path using a synthetic HandBrakeCLI harness and a real MP4 fixture

HandBrakeCLI is not installed in the work environment, so encoder-specific output quality was not assessed. The full test suite was intentionally skipped for this sprint.

Roadmap-Step: REN-02

Closes #345