Polish shared GUI and TUI discovery

[debpalash]

Summary

• share distribution search matching and result summaries between GPUI and Ratatui
• use word-prefix matching for one- and two-character queries so om no longer matches ChromeOS incidentally
• add explicit Select, Selected, Blocked, Refresh, and Retry labels in both adapters
• improve empty states, removable-media inventory clarity, catalog headings, version labels, and desktop opacity
• document the expanded GUI/TUI parity contract

Safety

• target selection remains explicit
• blocked, internal, system, and read-only media remain unselectable
• review, acknowledgment, and write confirmation paths are unchanged

Validation

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• 118 tests passed; 3 live or privileged integration tests ignored