Add comprehensive test coverage for fzf core modules

[maooc]

Pull Request: Add Comprehensive Test Coverage for fzf Core Modules

Generated by: Kimi AI Model

Summary

This PR adds unit tests to improve test coverage and boundary condition handling for the fzf project. All tests focus on edge cases, error handling, and boundary conditions that were not adequately covered by existing tests.

New Test Files

File	Description
src/algo/algo_extra_test.go	Tests for indexAt, empty pattern handling, EqualMatch, FuzzyMatchV2 position tracking, Init scoring schemes
src/ansi_extra_test.go	Tests for ansiState equals/colored methods, extractColor edge cases
src/functions_test.go	Tests for WriteTemporaryFile, stringBytes, byteString round-trip conversions
src/options_extra_test.go	Tests for parseAlgo, isAlphabet, isNumeric, parseBorder, atoi, atof, filterNonEmpty, isDir, firstLine, defaultOptions
src/reader_extra_test.go	Tests for trimPath functionality
src/server_test.go	Tests for parseListenAddress, IsLocal method
src/tokenizer_extra_test.go	Tests for ParseRange edge cases, Range.IsFull, compareRanges, RangesToString, awkTokenizer, Delimiter.IsAwk
src/util/util_additional_test.go	Tests for StringsWidth with tabs, overflow handling, Truncate edge cases, Constrain, AsUint16, RunOnce, RepeatToFill, ToKebabCase

Test Coverage Focus

The new tests specifically target:

• Empty input/empty string handling
• Unicode character processing
• Tab character expansion calculations
• Numeric overflow/boundary values (e.g., uint16 max value)
• Negative number handling
• Nil pointer handling
• Special character escaping (e.g., ANSI escape sequences)

Statistics

• 8 new test files
• 1240+ lines of test code
• All new tests pass successfully

Testing

Run the new tests with:

go test ./src/...
go test ./src/util/... -v
go test ./src/algo/... -v

Notes

• No external dependencies were added
• All tests are repeatable and stable
• No modifications to production code were required
• Tests follow existing project conventions and patterns