Fix: Allow reading large Claude session files by disabling size limit (#3166)

* Initial plan

* Fix: Allow reading large Claude session files by disabling size limit

- Pass disableLimit: true when reading Claude session files
- Update MockFileSystemService to accept disableLimit parameter
- Add test for large session files (>5MB)

Co-authored-by: TylerLeonhardt <2644648+TylerLeonhardt@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: TylerLeonhardt <2644648+TylerLeonhardt@users.noreply.github.com>