feat(object/deepFreeze): add deepFreeze function for recursively freezing objects

[sukvvon]

Summary

• Add deepFreeze function that recursively freezes an object and all nested objects/arrays
• Unlike Object.freeze, handles deep nesting and circular references
• 100% test coverage (8 test cases)
• Docs in all 4 languages (en, ko, ja, zh_hans)

Closes #1356

Test Plan

• Freeze nested objects
• Freeze nested arrays with nested objects
• Return the same object reference
• Handle primitives (number, string, null, undefined, boolean)
• Handle deeply nested objects
• Handle circular references
• Handle empty objects
• Prevent modifications in strict mode
• Full test suite passes (4339 tests)

[vercel]

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Project	Deployment	Actions	Updated (UTC)
es-toolkit	Ready	Preview, Comment	Apr 3, 2026 11:19am

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.97%. Comparing base (cd553ee) to head (232e6a8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1680   +/-   ##
=======================================
  Coverage   99.97%   99.97%           
=======================================
  Files         497      498    +1     
  Lines        4662     4672   +10     
  Branches     1348     1350    +2     
=======================================
+ Hits         4661     4671   +10     
  Misses          1        1           

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