refactor: move debug impls to owner packages and add BigInt internal debug

[bobzhang]

Summary

• Refactored Debug trait implementations out of the centralized debug package into their respective owner packages (hashmap, hashset, list, queue, deque, etc.), reducing coupling and improving maintainability
• Added @debug.Debug implementation for BigInt with internal debug support
• Fixed several bugs: list.scan_left double evaluation, priority_queue.copy() stack overflow, immut/array missing bounds checks, sorted_map.range() incorrect comments
• Performance improvements: hashmap.from_array avoids mid-build rehashing, string.Regex.replace_by delays StringBuilder allocation

Test plan

• CI passes all existing tests
• New tests for sorted_map.range(), priority_queue.copy(), immut/array bounds checking

🤖 Generated with Claude Code

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[coveralls]

Pull Request Test Coverage Report for Build 3167

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.742%

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Totals
Change from base Build 3162:	0.0%
Covered Lines:	13829
Relevant Lines:	14444

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💛 - Coveralls

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.