feat(walkie): support reliable dictation in terminals and remote desktops

[joeblau]

Walkie now supports volume-button dictation into local terminals and remote desktop tabs. Tap Volume Up/Down to select a workspace, hold Down to record, release to finalize and insert the transcript, and hold Up to execute after insertion. Each recording stays tied to its original terminal pane or VNC connection, even when focus changes.

The change flushes the final captured audio, shortens inferred button-release detection, cancels queued execution on interruptions, and retains unsent text on the phone. Remote computer tabs appear in Walkie and accept Unicode keyboard input without clipboard sharing. It also fixes remote group restoration writing preferences during rendering, which could freeze the Mac UI.

Validation:

• 169 shared iPhone tests passed, including queued Enter cancellation, transcript finalization, and volume gesture regressions.
• 87 targeted Mac tests passed across dictation routing, VNC keyboard input, connection lifecycle, and remote group selection/layout.
• Strict SwiftLint passed for all 27 changed Swift files; regenerating the Xcode project produced no differences.

Live physical iPhone-to-Mac-to-VNC validation remains outstanding. Volume release is inferred from public iOS volume-change events (approximately 0.7 seconds), and transport acceptance does not acknowledge insertion by the destination application.