feat: add orphan mod cleanup tool with GUI integration and live-server tests

- Add arma_modlist_tools/cleaner.py: find_orphan_folders() detects @ModName
  folders no longer referenced in comparison.json; uses _normalize_name from
  fetcher for consistent three-level matching
- Add clean_orphans.py: CLI with --dry-run and --yes/-y flags; junction-safe
  deletion via _is_junction() guard before shutil.rmtree
- Add Clean Orphans tab to gui/views/tools.py: scrollable checkbox list,
  background scan/delete threads, pending-done-msg pattern for post-scan
  status, EN/VI localization strings in gui/locales.py
- Add 23 unit tests (section 12), 6 E2E subprocess tests (section 13),
  23 coverage-gap tests (section 14), 9 live-server fetcher tests (section 15)
- Fix leaked builtins.open mock in _test_read_os_release_parses_file
- Overall coverage: 84% → 93%; fetcher.py: 36% → 72%

clean_orphans.py

@@ -0,0 +1,127 @@
+#!/usr/bin/env python3
+"""
+CLI entry point: find and remove orphaned mod folders from downloads/.
+
+An orphan is a downloads/{group}/@ModName folder that is no longer referenced
+by any group in comparison.json.  These accumulate when presets change and
+the pipeline is re-run without cleaning up old folders.
+
+Usage:
+    python clean_orphans.py               # list orphans, ask for confirmation
+    python clean_orphans.py --dry-run     # list orphans, do not delete
+    python clean_orphans.py --yes         # list and delete without prompting
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import shutil
+import sys
+
+from arma_modlist_tools.cleaner import find_orphan_folders
+from arma_modlist_tools.compat import fix_console_encoding
+from arma_modlist_tools.config import load_config
+from arma_modlist_tools.linker import _is_junction, remove_junction
+
+fix_console_encoding()
+
+_UNITS = ("B", "KB", "MB", "GB", "TB")
+
+
+def _fmt_size(n: int) -> str:
+    for unit in _UNITS:
+        if n < 1024:
+            return f"{n:.1f} {unit}"
+        n /= 1024
+    return f"{n:.1f} PB"
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="Find and remove orphaned mod folders from downloads/."
+    )
+    parser.add_argument(
+        "--dry-run",
+        action="store_true",
+        help="List orphans but do not delete anything.",
+    )
+    parser.add_argument(
+        "--yes", "-y",
+        action="store_true",
+        help="Delete without prompting for confirmation.",
+    )
+    args = parser.parse_args()
+
+    cfg = load_config()
+
+    if not cfg.comparison.exists():
+        print(f"ERROR: {cfg.comparison} not found. Run compare_modlists.py first.")
+        sys.exit(1)
+
+    comparison = json.loads(cfg.comparison.read_text(encoding="utf-8"))
+
+    print(f"\nScanning {cfg.downloads} for orphaned mod folders...\n")
+    orphans = find_orphan_folders(cfg.downloads, comparison)
+
+    if not orphans:
+        print("  No orphans found. Your downloads folder is clean.")
+        print()
+        return
+
+    total_size = sum(o["size"] for o in orphans)
+    print(f"  {'Group':<28}  {'Folder':<32}  Size")
+    print(f"  {'-'*28}  {'-'*32}  {'-'*10}")
+    for o in orphans:
+        print(f"  {o['group']:<28}  {o['name']:<32}  {_fmt_size(o['size'])}")
+
+    print()
+    print(f"  {len(orphans)} orphan(s) found — {_fmt_size(total_size)} total")
+    print()
+
+    if args.dry_run:
+        print("  --dry-run: nothing deleted.")
+        print()
+        return
+
+    if not args.yes:
+        answer = input("  Delete all orphans? [y/N] ").strip().lower()
+        if answer not in ("y", "yes"):
+            print("  Aborted.")
+            print()
+            return
+
+    deleted = 0
+    freed = 0
+    errors = 0
+    for o in orphans:
+        p = o["path"]
+        try:
+            if _is_junction(p):
+                # Safety: never rmtree a junction — use remove_junction() which
+                # calls os.rmdir() and removes only the pointer, not the target.
+                ok, err = remove_junction(p)
+                if not ok:
+                    print(f"  ERROR: could not remove junction {p.name}: {err}")
+                    errors += 1
+                    continue
+            else:
+                shutil.rmtree(p)
+            deleted += 1
+            freed += o["size"]
+            print(f"  Deleted: {o['group']}/{o['name']}")
+        except Exception as e:
+            print(f"  ERROR: {p.name}: {e}")
+            errors += 1
+
+    print()
+    print(f"  Done: {deleted} deleted, freed {_fmt_size(freed)}"
+          + (f", {errors} error(s)" if errors else ""))
+    print()
+
+    if errors:
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()