Function scoreToChar

scoreToChar(
score: number | QualityScore | SolexaScore,
encoding: QualityEncoding,
): string
Convert a numeric quality score to ASCII character with type safety
Parameters
- score: number | QualityScore | SolexaScore
  Numeric quality score (accepts branded QualityScore/SolexaScore or validated number)
- encoding: QualityEncoding
  Quality encoding scheme ('phred33', 'phred64', or 'solexa')
Returns string
ASCII quality character for the encoding
Throws
When score is not a valid integer

Throws
When score is outside QualityScore range (0-93) for non-Solexa

Throws
When score is outside encoding-specific valid range
Example
```
// Phred+33 (modern standard)
scoreToChar(40, 'phred33'); // Returns 'I' (ASCII 73)
scoreToChar(0, 'phred33');  // Returns '!' (ASCII 33)
scoreToChar(93, 'phred33'); // Returns '~' (ASCII 126)

// Phred+64 (legacy)
scoreToChar(40, 'phred64'); // Returns 'h' (ASCII 104)
scoreToChar(0, 'phred64');  // Returns '@' (ASCII 64)

// Type-safe with branded types
const validated = 40 as QualityScore;
scoreToChar(validated, 'phred33'); // Type-safe, no runtime validation needed
```
Performance
O(1) - Direct calculation with constant time validation

Since
v0.1.0
- Defined in src/operations/core/quality/conversion.ts:106