a00f6edda4
Add comprehensive unit tests for the deep-merge.ts utility functions: - isPlainObject: 11 test cases covering null, undefined, primitives, Array, Date, RegExp, and plain objects - deepMerge: 15 test cases covering: - Basic object merging - Deep nested object merging - Edge cases (undefined handling) - Array replacement behavior - Prototype pollution protection (DANGEROUS_KEYS) - MAX_DEPTH limit handling