refactor: collapse micro-modules, add AUR packaging

- domain/ (7 files) → domain.rs + error.rs + window.rs
- protocols/sftp/ (4 files) → sftp.rs, ftp/ (3 files) → ftp.rs
- storage/db/ (6 files) → storage.rs + settings.rs
- transfer/ (5 files) → transfers/{queue,worker}.rs
- add dist/PKGBUILD, .SRCINFO, wherry.desktop for AUR
- fix all import paths, 53 tests pass

src/fs/local.rs

@@ -1,4 +1,4 @@
-use crate::domain::file_entry::{EntryKind, FileEntry};
+use crate::domain::{EntryKind, FileEntry};
 use anyhow::Result;
 use std::fs;