Allow common loop variables in unicorn/prevent-abbreviations rule
- **unicorn/prevent-abbreviations**: Allow `i`, `j`, `k` as idiomatic variable names
- These are universally recognized as loop counters and array indices
- Prevents unnecessary renaming in common patterns like:
- `for (let i = 0; i < array.length; i++)`
- `array.forEach((item, i, arr) => ...)`
- Matrix operations with `i`, `j`, `k` indices
- Added comprehensive tests for the new configuration
- Modified `src/configs/unicorn.ts` to include `j` and `k` alongside existing `i`
- Added to both `allowList` (permits usage) and `omitReplacementList` (prevents suggestions)
- Created new test suite in `src/configs/__tests__/unicorn.test.ts` to verify:
- Rule configuration structure
- All three variables are allowed
- No replacement suggestions are made for these variables
- Other common abbreviations remain allowed
- Reduces friction when writing loops and array operations
- Maintains consistency with mathematical and programming conventions
- Eliminates noisy linting errors for these standard variable names
This patch release improves developer ergonomics without compromising code quality standards.