Extract shared mail routing and IMAP folder helpers

Prompt since previous commit: execute step 1

Centralized route targets, source-folder policy, and modified UTF-7 mailbox quoting. Verification: py_compile, route/folder consistency, and git diff --check passed.

download_mailbox.py

@@ -13,23 +13,13 @@ import re
 import sys
 import getpass
 from pathlib import Path
+from imap_utils import list_folders, quote_mailbox
 
 IMAP_HOST = "australius.nl"
 IMAP_PORT = 993
 LOCAL_DIR = Path(__file__).parent / "mailbox"
 
 
-def parse_folder_name(line: bytes) -> str | None:
-    """Haal mapnaam op uit IMAP LIST-response."""
-    decoded = line.decode("utf-8", errors="replace")
-    # Formaat: (\Flags) "delimiter" "naam" of (\Flags) "delimiter" naam
-    match = re.match(r'\(.*?\)\s+".*?"\s+(.*)', decoded)
-    if not match:
-        return None
-    name = match.group(1).strip().strip('"')
-    return name if name else None
-
-
 def safe_path(name: str) -> str:
     """Zet mapnaam om naar een veilige directorynaam."""
     return re.sub(r'[<>:"/\\|?*\x00-\x1f]', "_", name)
@@ -49,15 +39,11 @@ def download():
 
     print("Ingelogd.\n")
 
-    # Alle mappen ophalen
-    status, raw_folders = mail.list()
-    if status != "OK":
+    folders = list_folders(mail)
+    if not folders:
         print("Kan mappenlijst niet ophalen.")
         sys.exit(1)
 
-    folders = [parse_folder_name(f) for f in raw_folders if f]
-    folders = [f for f in folders if f]
-
     print(f"Gevonden mappen ({len(folders)}):")
     for f in folders:
         print(f"  {f}")
@@ -69,8 +55,7 @@ def download():
     for folder_idx, folder in enumerate(folders, 1):
         folder_prefix = f"[map {folder_idx}/{num_folders}] {folder}"
 
-        quoted = f'"{folder}"'
-        status, data = mail.select(quoted, readonly=True)
+        status, data = mail.select(quote_mailbox(folder), readonly=True)
         if status != "OK":
             print(f"{folder_prefix}: kan niet openen – overgeslagen.")
             continue