fix: remove session compression to improve performance

[lambdalisue]

Summary

• Removed brotli compression from session saving/loading to improve performance
• Made savePickerSession and loadPickerSession synchronous functions
• Updated documentation to reflect the change

Background

Session compression was causing performance issues when saving picker sessions. By removing the compression overhead, sessions are now saved and loaded much faster.

Changes

• Removed brotli compression dependency from session.ts
• Removed PickerSessionCompressed type and related compression/decompression functions
• Updated savePickerSession to be synchronous (no longer returns a Promise)
• Updated loadPickerSession to be synchronous (no longer returns a Promise)
• Updated all files that use these functions to handle synchronous behavior
• Updated documentation in doc/fall.txt to remove mention of compression

Test plan

• All existing tests pass
• No lint errors
• Type checking passes
• Session saving and loading works correctly without compression

🤖 Generated with Claude Code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.77%. Comparing base (2c66097) to head (f55583b).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
- Coverage   82.09%   81.77%   -0.33%     
==========================================
  Files          26       26              
  Lines        1793     1761      -32     
  Branches      178      176       -2     
==========================================
- Hits         1472     1440      -32     
  Misses        318      318              
  Partials        3        3              

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