Make the shared client a superset of what todo's and diet_guard-app's local
GitHubClient copies provide, so every app can drop its copy and sync through
one client. canAccessRepo() is a lightweight connection test (bare repo GET,
never throws); deleteFile() resolves the file's own sha and no-ops when
absent. Mirrored on the Dart and Python sides. 90 Dart + 78 Python tests, 100%.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019KwUCPESvE5CjCtmUFz8xQ
Pure-Dart mirror of the Python crdt-sync package, module-for-module and
test-for-test, so the merge algorithm canonically agrees on both sides of
a sync between a Dart client and a Python one. No Flutter SDK dependency
(package:http only) per Workstream D's scoping decision (2026-07-04).
59 tests, clean dart analyze.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017McuA1nAi6jBT1EaS5BrVf
