Closes #501 searchEmails now queries the local email_fts virtual table filtered by mailbox_path instead of doing a live IMAP SEARCH. This makes folder-view search work offline and ensures tapped results always open the correct email (IDs come from the same local DB that getEmail reads from). Reuses the existing FTS5 infrastructure (_toFtsQuery + the email_fts content-table join) from searchEmailsGlobal, adding only the `AND e.mailbox_path = ?` filter. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>