Function default

default(r: string): number
Converts Roman numerals to numbers for parsing pattern notes in playSequence.

When playing musical patterns, notes can be specified as Roman numerals (I, II, III, etc.) representing scale degrees. This function converts them to numbers so we can find the correct pitch in the scale. Supports + and - prefixes for octave shifts.

Used in sound-context.tsx playSequence function to parse pattern note degrees like "V" → 5th scale degree, "+II" → 2nd degree in higher octave.
Parameters
- r: string
  Roman numeral (I-XII), optionally prefixed with + or -
Returns number
Number 1-12, or 0 if invalid
Example
```
romanToNumber("V") // 5 (fifth scale degree)
romanToNumber("+IV") // 4 (fourth degree, higher octave)
romanToNumber("-II") // 2 (second degree, lower octave)
```
- Defined in functions/romanToNumber.ts:19