Synced from monorepo

Synced from monorepo

Changes:
- Remove the project-directory picker
- External-binary auth: treat sign-in as a fresh login, not a refresh
- Skip nested checkouts in file watching so in-repo worktrees cannot stall startup
- Count model-side skill reads in telemetry and restore the skill-dispatched trigger
- State the real size when short tool output is only part of the log
- Emit git-head-changed on same-branch commits
- Apply pre-session model selection optimistically

Source-Revision: 27d2088ae3b3f25e9ddab462caa18a07005ada9a