fix: convert named Strudel notes when freezing to MIDI

[beejsbj]

Description

Freezing a Strudel melody written with note names creates no MIDI track. Numeric note values work, but normal values such as "d4" are coerced through Number(...) and become NaN before MIDI conversion.

Tested commit: 2bebdd2cbaaef1092a06ff613c7868c9f3bd4b6c.

Steps to Reproduce

1. Create a Strudel track in the web app.
2. Set its code to:

note("d4 f4 a4").s("triangle")

3. Choose Freeze to MIDI for one bar.
4. Repeat with note("62 65 69").s("triangle") as a control.

Expected Behavior

Both forms create a piano-roll track containing the corresponding MIDI notes (d4 = 62, f4 = 65, a4 = 69).

Actual Behavior

The named-note form returns no MIDI track because every note is discarded as NaN; the numeric control creates MIDI notes.

Environment

• Browser: Google Chrome 147.0.7727.101 (headless Playwright)
• OS: Ubuntu 24.04.3 LTS
• Node version: 24.13.0
• Audio path: web / Tone.js

Screenshots / Logs

queryPatternEvents applies Number(noteVal), and strudelEventsToMidiNotes filters NaN. The freeze action then returns null for an empty note list (source).

Acceptance Criteria

• note("d4 f4 a4") freezes to a piano-roll track with pitches 62, 65, and 69.
• Numeric-note conversion continues to work.
• Invalid note values fail predictably without emitting NaN MIDI pitches.
• Regression tests cover both named and numeric Strudel note values.
• Fix passes all quality gates.