Summary

Closes #25

Makes the BPM slider control the actual transport tempo used by clip playback scheduling. Tempo changes now update audio-engine transport state, and active playback uses the new tempo for future lookahead scheduler windows.

Changes

• Adds shared tempo constants and clampTempoBpm for the 60-180 BPM transport range.
• Wires the app BPM slider to audioEngine.setTempoBpm instead of only updating local display state.
• Adds a mutable scheduler tempo update path that preserves the current runtime tick while playback is active.
• Passes scheduler tempo through scheduled events so pitched note durations use the tempo active for that scheduling window.
• Keeps stopped and paused tempo changes available for the next play/resume action.
• Marks the tempo feature spec as in review and notes Tempo control and live BPM updates #25 in PLANS.md.
• Adds unit tests for tempo clamping and live scheduler tempo updates.

Testing

• npm run typecheck --if-present
• npm run lint --if-present
• npm run test --if-present
• npm run build --if-present

Screenshots

Not included. Dev server was started and the app returned HTTP 200 at http://127.0.0.1:5174/ because port 5173 was already in use.

Notes / Limitations

• Tempo changes affect future scheduler windows. Events already submitted to Web Audio inside the current short lookahead window may still use the previous tempo briefly.
• No tempo automation, tap tempo, metronome, or arrangement tempo map is included.
• Manual audible tempo-change review still needs browser playback.