Improve encapsulation in IMAP classes

Make all attributes private (_host, _imap, etc.) and remove redundant
public connect/disconnect methods. Connection management is now handled
internally by the orchestrator calling private _connect/_disconnect.

Changes:
- Privatize ImapClient attributes and methods
- Update EmailForwarder to call private connection methods
- Enhance encapsulation without changing functionality

main.py

@@ -15,34 +15,26 @@ class ImapClient:
     """Base class for IMAP operations."""
 
     def __init__(self, host: str, port: int, user: str, password: str):
-        self.host = host
-        self.port = port
-        self.user = user
-        self.password = password
-        self.imap = None
-
-    def connect(self):
-        """Establish IMAP connection."""
-        self._connect()
-
-    def disconnect(self):
-        """Close IMAP connection."""
-        self._disconnect()
+        self._host = host
+        self._port = port
+        self._user = user
+        self._password = password
+        self._imap = None
 
     def _connect(self):
         """Private: Connect and login to IMAP."""
-        self.imap = imaplib.IMAP4_SSL(self.host, self.port)
-        self.imap.login(self.user, self.password)
+        self._imap = imaplib.IMAP4_SSL(self._host, self._port)
+        self._imap.login(self._user, self._password)
 
     def _disconnect(self):
         """Private: Logout and close connection."""
-        if self.imap:
-            self.imap.logout()
-            self.imap = None
+        if self._imap:
+            self._imap.logout()
+            self._imap = None
 
     def _list_folders(self):
         """Private: List all folders."""
-        typ, data = self.imap.list()
+        typ, data = self._imap.list()
         if typ != "OK":
             raise Exception("Failed to list folders")
         folders = []
@@ -56,20 +48,20 @@ class ImapClient:
 
     def _select_folder(self, folder: str):
         """Private: Select a folder."""
-        typ, _ = self.imap.select(folder)
+        typ, _ = self._imap.select(folder)
         if typ != "OK":
             raise Exception(f"Failed to select folder {folder}")
 
     def _search(self, criteria: str):
         """Private: Search emails."""
-        typ, data = self.imap.search(None, criteria)
+        typ, data = self._imap.search(None, criteria)
         if typ != "OK":
             raise Exception(f"Search failed: {criteria}")
         return data[0].split()
 
     def _fetch(self, uid: str):
         """Private: Fetch raw email."""
-        typ, data = self.imap.fetch(uid, "(RFC822)")
+        typ, data = self._imap.fetch(uid, "(RFC822)")
         if typ != "OK":
             raise Exception(f"Failed to fetch UID {uid}")
         return data[0][1]
@@ -120,13 +112,13 @@ class DestImap(ImapClient):
 
     def _create_folder(self, folder: str):
         """Private: Create a folder."""
-        typ, _ = self.imap.create(folder)
+        typ, _ = self._imap.create(folder)
         if typ != "OK":
             raise Exception(f"Failed to create folder {folder}")
 
     def _append(self, folder: str, msg: bytes):
         """Private: Append message to folder."""
-        self.imap.append(folder, "", None, msg)
+        self._imap.append(folder, "", None, msg)
 
 
 class EmailForwarder: