feat: add native apps workbench

[keys-i]

Part of #1.

Depends on #7.

Summary

• add the dependency-free native apps binary for bounded text search, quoted CSV/TSV inspection, Markdown slides, text-canvas paint, and monotonic timers
• preserve stable plain/JSON snapshots, bounded terminal rendering, control-safe metadata, and atomic no-overwrite paint saves
• include the sixth binary in the wheel smoke, benchmark workflow, research record, and package documentation

Impact

This replaces launcher/catalog behavior with five owned local workflows while keeping Crossterm as the only runtime dependency. Browser, PDF, compositor, PTY, TLS, and live-service engines remain deliberately excluded.

Verification

• cargo fmt --all --check
• cargo clippy --all-targets --locked -- -D warnings
• cargo test --locked (25 unit tests, 7 CLI tests, doc tests)
• cargo build --release --locked --bin apps
• hostile OSC filename CLI regression and native PTY restoration smoke
• Maturin wheel build and isolated smoke for all six binaries, license notice included
• Hyperfine: 100 runs after 20 warmups, 1.6 ± 0.1 ms, 1.4–1.9 ms; stripped binary 438,752 bytes

Risk and rollback

Inputs are local, UTF-8, bounded, and non-destructive except explicit paint output, which refuses existing targets. Roll back commit ac3bc9b to remove the binary and package integration.