test: add comprehensive edge case tests

[aeromomo]

Adds 30+ test cases covering:

• Long filename handling (boundary conditions at 255/256 bytes)
• Search edge cases (None guards, empty results, post-deletion)
• Duplicate file handling (case sensitivity, unicode normalization)
• Text compression edge cases (empty, emoji-only, 1MB, binary-like)
• Concurrent operation safety (20 parallel writes, mixed search/write)
• Unicode edge cases (zero-width, RTL, combining chars, surrogate pairs)
• Security (path traversal, null bytes, deeply nested JSON)

Includes both full test suite (test_edge_cases.py) for modern Python/async and simplified version (test_edge_cases_simple.py) that runs on older Python.

These tests expose potential boundary conditions and race conditions that might not be covered in regular testing. Some may fail on current codebase

• these highlight areas for improvement.

Description

Related Issue

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

[CLAassistant]

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