Three pre-existing issues in the visual test runner were never caught
because visual tests aren't run in CI. Fix all three and add visual
tests to the macOS CI job so they stay healthy going forward.

1. Re-entrant read panic in sidebar creation (3 places): Sidebar::new
   reads the MultiWorkspace entity, so creating it inside a
   multi_workspace.update() closure causes a double-borrow panic.
   Fix by using update_window with root_view.downcast() instead.

2. Tooltip entity leak in breakpoint_hover test: The tooltip system has
   an Rc cycle (ActiveTooltip::Visible holds a check_visible_and_update
   closure that captures the Rc<RefCell<Option<ActiveTooltip>>>). This
   cycle is normally broken when the tooltip is dismissed, but the test
   closed the window while the tooltip was still visible. Fix by
   simulating a click before cleanup to dismiss the tooltip.

3. Visual tests not in CI: Add a cargo_run_visual_tests step to the
   macOS test job via xtask so these tests run on every PR.

…t-panics

…t-panics

Extract the tab disambiguation algorithm from pane.rs into a generic
util::disambiguate module, then use it to disambiguate sidebar project
group names when multiple projects share the same leaf directory name.

The disambiguation works at the individual path level across all groups,
so even a multi-worktree group like 'code/zed + bar/zed' gets each of
its paths disambiguated independently against paths from other groups.

Also adds visual tests covering the two-project and three-project
(with multi-worktree) scenarios.

- Optimize path_suffix to use reverse iteration instead of collecting all components
- Remove unused display_name method, rename display_name_from_suffixes to display_name
- Add doc comment warning about fixed-point requirement on compute_disambiguation_details
- Apply disambiguation to project picker (get_recent_projects and get_open_folders)

# Conflicts:
#	crates/sidebar/src/sidebar.rs

When the same path appears in multiple project groups (e.g. /code/zed in
both a 'zed' group and a 'zed, roc' group), the flat_map produced
duplicates that compute_disambiguation_details treated as perpetually
colliding items, driving the detail level to the full absolute path.

Fix by deduplicating paths before disambiguating. Add a regression test
that verifies the correct behavior with the real path_suffix logic.