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.

dagelijks_overzicht.py

@@ -26,6 +26,7 @@ from pathlib import Path
 from collections import defaultdict
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
+from imap_utils import list_folders, quote_mailbox
 
 # Mappen die NIET in het overzicht komen (systeem + inbox zelf)
 UITSLUITINGEN = {
@@ -86,14 +87,6 @@ def leesbare_map(imap_naam: str) -> str:
     return imap_naam.removeprefix("INBOX.").replace(".", " › ")
 
 
-def parse_folder_name(raw: bytes) -> str | None:
-    decoded = raw.decode("utf-8", errors="replace")
-    m = re.match(r'\(.*?\)\s+".*?"\s+(.*)', decoded)
-    if m:
-        return m.group(1).strip().strip('"')
-    return None
-
-
 # ── IMAP ophalen ──────────────────────────────────────────────────────────────
 
 def haal_berichten_op(mail: imaplib.IMAP4_SSL, zoekdatum: date) -> dict[str, list[dict]]:
@@ -104,13 +97,10 @@ def haal_berichten_op(mail: imaplib.IMAP4_SSL, zoekdatum: date) -> dict[str, lis
     since  = imap_date(zoekdatum)
     before = imap_date(zoekdatum + timedelta(days=1))
 
-    status, raw_folders = mail.list()
-    if status != "OK":
+    alle_mappen = list_folders(mail)
+    if not alle_mappen:
         return {}
 
-    alle_mappen = [parse_folder_name(f) for f in raw_folders if f]
-    alle_mappen = [f for f in alle_mappen if f]
-
     resultaat: dict[str, list[dict]] = defaultdict(list)
 
     for folder in sorted(alle_mappen):
@@ -119,7 +109,7 @@ def haal_berichten_op(mail: imaplib.IMAP4_SSL, zoekdatum: date) -> dict[str, lis
         if UITSLUIT_PATRONEN.match(folder):
             continue
 
-        status, data = mail.select(f'"{folder}"', readonly=True)
+        status, data = mail.select(quote_mailbox(folder), readonly=True)
         if status != "OK":
             continue