git: discover worktrees when opening a worktree directory

When a worktree directory is opened with `git.detectWorktrees` enabled,
`checkForWorktrees()` previously returned early without discovering the
main repository or sibling worktrees. This left worktree management
commands non-functional because:

- Commands like "Create Worktree" filter for repository/submodule kind
- "Open Worktree" requires gitOpenRepositoryCount > 1
- SCM menu items depend on a repository-kind provider being open

Remove the early return for worktree-kind repositories and instead
always filter out the current repository from the candidate list. This
enables bidirectional worktree discovery (worktree → main repo, and
main repo → worktrees) and also fixes a pre-existing off-by-one in the
limit/warning logic where the main repo counted itself as a candidate.

The existing `isRepositoryOutsideWorkspace()` check already allows this
because it recognizes paths that appear in any open repository's worktree
list, and `getRepositoryExact()` prevents duplicate/recursive opens.

Also fixes a confusing log message that said detection "is not skipped"
when it was in fact skipping.

Fixes #264209

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: marcelsafin

extensions/git/src/model.ts

@@ -807,17 +807,17 @@ export class Model implements IRepositoryResolver, IBranchProtectionProviderRegi
 				return;
 			}
 
-			if (repository.kind === 'worktree') {
-				this.logger.trace('[Model][open] Automatic detection of git worktrees is not skipped.');
-				return;
-			}
+			// Discover additional worktrees for the repository, but do not
+			// include the currently opened repository itself.
+			const candidateWorktrees = repository.worktrees
+				.filter(w => !pathEquals(w.path, repository.root));
 
-			if (repository.worktrees.length > worktreesLimit) {
-				window.showWarningMessage(l10n.t('The "{0}" repository has {1} worktrees which won\'t be opened automatically. You can still open each one individually by opening a file within.', path.basename(repository.root), repository.worktrees.length));
+			if (candidateWorktrees.length > worktreesLimit) {
+				window.showWarningMessage(l10n.t('The "{0}" repository has {1} worktrees which won\'t be opened automatically. You can still open each one individually by opening a file within.', path.basename(repository.root), candidateWorktrees.length - worktreesLimit));
 				statusListener.dispose();
 			}
 
-			repository.worktrees
+			candidateWorktrees
 				.slice(0, worktreesLimit)
 				.forEach(w => {
 					this.logger.trace(`[Model][open] Opening worktree: '${w.path}'`);