* fix(server): keep Git observation and worktree IO off the event loop
Resolve subscription path identities before callbacks and serialize async worktree metadata mutations by canonical ownership. Git command tracing must not probe the working directory before spawning.
* test(server): verify Git trace records without filesystem probes
* fix(server): establish Git identities at observation setup
Read-only checkout refreshes should not resolve watcher namespaces. Observation tests await setup and compare cross-workspace fan-out without depending on completion order.
* fix(server): retain literal symlink targets in Git event identity
Canonical realpaths can erase a symlink target spelling when its parent is also a symlink, such as /var on macOS. Resolve these aliases once during setup so deleted and ignored event paths still match without per-event IO.
* fix(server): preserve Windows worktree path spelling
* fix(server): retain native aliases in worktree ownership
* test(server): write Git IO trace markers asynchronously