fix(add-repository): make local repository dialog submission reliable

Tighten the Add Local Repository dialog so choosing a valid repository path and immediately pressing Add consistently runs the add flow instead of silently stalling in the dialog.

Changes:
- resolve the entered local path before submit-time validation so `validatePath(...)` uses the same normalized path handling as the live `onPathChanged(...)` validation path
- wait for the folder-picker path to finish landing in component state before allowing the chosen path to be used for submission
- keep the rest of the add-existing-repository flow unchanged so successful submissions still dismiss the dialog, add the repository, and select it

Behavioral effect:
The Add Local Repository dialog no longer ends up in a no-op state where a repository path appears valid in the picker flow but submit-time validation never reaches `_addRepositories(...)`. Choosing a worktree path from the folder picker and immediately pressing Add now reliably adds the repository.

Testing:
- yarn eslint app/src/ui/add-repository/add-existing-repository.tsx
- yarn compile:prod

Author: ignatremizov

app/src/ui/add-repository/add-existing-repository.tsx

@@ -77,7 +77,9 @@ export class AddExistingRepository extends React.Component<
   }
 
   private async updatePath(path: string) {
-    this.setState({ path })
+    await new Promise<void>(resolve => {
+      this.setState({ path }, resolve)
+    })
   }
 
   private async validatePath(path: string): Promise<boolean> {
@@ -89,7 +91,8 @@ export class AddExistingRepository extends React.Component<
       return false
     }
 
-    const type = await getRepositoryType(path)
+    const resolvedPath = this.resolvedPath(path)
+    const type = await getRepositoryType(resolvedPath)
 
     const isRepository = type.kind !== 'missing' && type.kind !== 'unsafe'
     const isRepositoryUnsafe = type.kind === 'unsafe'