feat(email): add digest and forward commands to WhatsApp

Digest summarizes unread emails via Claude CLI; forward sends raw
content (split to 4096 chars). Wired as /email digest and
/email forward slash commands, plus instant per-guild sync on ready.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/email_process.py

@@ -193,7 +193,9 @@ def save_email_as_note(eid: str) -> dict:
         'ok': True,
         'file': str(filepath),
         'subject': subject,
-        'from': sender_email
+        'from': sender_email,
+        'from_full': from_addr,
+        'date': date_str,
     }
 
 def save_unread_emails():