Show permission errors immediately when navigating to restricted folders

[BrianLeishman]

Summary

When navigating to a folder that requires permissions (like macOS Trash), the app shows a spinner indefinitely. The error only appears after manually refreshing. The error should display immediately, and clicking "OK" should navigate back to the previous location or home folder.

Current State

• File: src/store/useAppStore.ts:507-609 (navigateTo function)
• File: src/store/useAppStore.ts:711-780 (refreshCurrentDirectory function)
• Navigation calls refreshCurrentDirectory which catches errors and sets error state
• However, errors from permission issues don't trigger immediate UI feedback - just an endless spinner
• After reload, error dialog shows: "Failed to refresh: Failed to read directory: Operation not permitted (os error 1)"
• Clicking "OK" leaves user on the broken path with no way to navigate away easily

Proposed Changes

1. Immediate error feedback: When navigateTo fails due to permission errors, show the error dialog immediately instead of leaving the spinner running
2. Navigate away on dismiss: When user clicks "OK" on the permission error dialog:
   • Navigate back to the previous history location if available (goBack())
   • Or navigate to home folder if no history exists
3. Better error messaging: Include actionable guidance in the error message (e.g., "Grant access under System Settings → Privacy & Security → Files and Folders")

Technical Notes

• The navigateTo function at line 507 updates path history before directory contents are loaded
• The refreshCurrentDirectory function catches errors at line 758 but only sets error state
• Need to either: roll back history on failure, or not commit to history until directory loads successfully
• Consider using message() dialog (from Tauri) for permission errors instead of just setting error state

Acceptance Criteria

• Permission errors show immediately when navigating (no endless spinner)
• Error dialog displays with clear guidance on how to fix permissions
• Clicking "OK" navigates user back to previous location or home
• Path bar doesn't show the failed path after dismissing error