Add copy-to-clipboard audio diagnostics report

[DasAmpharos]

Summary

After a timer run completes, collect the performance.measure() entries already recorded for each audio action and expose them as a formatted diagnostics report the user can copy to the clipboard.

Motivation

When users report a first-audio-cue delay, there's currently no easy way to gather timing data without asking them to record a Chrome Performance trace. A one-click copy button gives us the data we need with zero DevTools knowledge required from the user.

Proposed UX

• A "Copy diagnostics" button (or icon) that appears after a run finishes, likely in the timer controls area or a small post-run overlay
• Clicking it formats the audio timing data as plain text and writes it to the clipboard
• User pastes directly into a GitHub issue

Data to include

For each action fired during the run:

• IPC latency (worker postMessage → main thread onmessage)
• Dispatch-to-initiation time (message received → src.start() called)
• Playback duration (onended − src.start())
• Whether it was the first action in the phase

Plus environment metadata:

• Browser user agent
• AudioContext.sampleRate and baseLatency / outputLatency
• AudioContext.state at run start

Implementation notes

The performance.measure() entries for audio:beep (and other sounds) are already being recorded — see src/audio/sounds.ts. The main work is:

1. Accumulating per-action timing in usePhaseRunner during the run
2. Exposing it after finished is received
3. Formatting + navigator.clipboard.writeText()