🧪 [testing improvement] Add test for HashMap resize logic

[void0x14]

🎯 What: Added a missing test for the HashMap resize logic.
📊 Coverage: The new test covers the "happy path" of triggering a single resize by inserting elements beyond the 0.75 load factor threshold (e.g., 7 items into a capacity 8 map) and asserting the preservation of all elements as well as verifying internal length/count state.
✨ Result: Enhanced unit test coverage for the core HashMap structure's dynamic allocation behavior, helping catch regressions or logic failures around reallocation in Zig code.

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PR created automatically by Jules for task 2245464762965517713 started by @ulac000000

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