Support string[] and Buffer in stringPlayable block

[Copilot]

stringPlayable only accepted string, while the underlying StringArrayPlayable constructor already handled string | string[] | Buffer. This mismatch prevented callers from passing note arrays or Buffers through the block API.

Changes

• libs/core/playable.ts: Widened stringPlayable parameter type from string to string | string[] | Buffer — no logic change needed since StringArrayPlayable already dispatches correctly for all three types
• libs/core/_locales/core-jsdoc-strings.json: Updated the generated locale string to reflect the new accepted types

Example

// Previously only worked with string
music.play(music.stringPlayable("E D G F B A C5 B", 120), music.PlaybackMode.UntilDone);

// Now also works with string[]
music.play(music.stringPlayable(["E", "D", "G", "F"], 120), music.PlaybackMode.UntilDone);

// And Buffer
music.play(music.stringPlayable(melodyBuffer, 120), music.PlaybackMode.UntilDone);

[abchatra]

Fixes #6965