fix: improve file read state error messages

[zhanba]

Summary

• improve file-edit error messages to distinguish files never read in available task history from files whose current read snapshot is no longer available
• retain lightweight read history across task resumes and cache eviction so the error message has enough context
• hydrate historical file operations consistently in CLI, background tasks, and VS Code

Test plan

• bun check
• bun tsc
• common FileStateCache tests
• livekit task utility and TaskExecutor tests
• VS Code FileStateCacheRegistry tests
• full pre-push test suite

🤖 Generated with Pochi | Task

[codecov-commenter]

Codecov Report

❌ Patch coverage is 67.29560% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 34.71%. Comparing base (156bb05) to head (04273a4).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/cli/src/running-task-adaptor.ts	0.00%	19 Missing ⚠️
packages/cli/src/task-runner.ts	0.00%	11 Missing ⚠️
packages/vscode-webui/src/features/chat/page.tsx	9.09%	10 Missing ⚠️
...scode/src/integrations/webview/vscode-host-impl.ts	0.00%	8 Missing ⚠️
...scode-webui/src/lib/vscode-running-task-adaptor.ts	0.00%	3 Missing ⚠️
packages/vscode-webui/src/lib/vscode.ts	0.00%	1 Missing ⚠️

❌ Your patch status has failed because the patch coverage (67.29%) is below the target coverage (75.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1881      +/-   ##
==========================================
+ Coverage   29.30%   34.71%   +5.40%     
==========================================
  Files         768      767       -1     
  Lines       80030    80167     +137     
  Branches     3846     3366     -480     
==========================================
+ Hits        23456    27831    +4375     
+ Misses      56455    52222    -4233     
+ Partials      119      114       -5     

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