## Why
A checkout could point its `.git` file at a trusted repository's worktree
directory without proving that the repository had registered that checkout.
This could cause project configuration from an unrelated checkout to be treated
as trusted.
## What changed
- Verify the linked worktree's `gitdir` backlink, `commondir`, registered
checkout, and main checkout ownership before resolving the main repository's
trust key.
- Reject missing, oversized, symlinked, mismatched, or swapped Git metadata.
- Preserve valid linked worktrees that use path aliases, separate Git
directories, or non-UTF-8 POSIX paths.
## Testing
Add resolver and config-loading coverage for forged worktrees, metadata races,
case-sensitive paths, moved worktrees, and host MCP startup from project config.
GitOrigin-RevId: 6052a7d10ad2d613436f20175c356abdef8c758e
