Add Fastmail email and calendar, multi-account neomutt

- mbsync: add Fastmail IMAP channel (rbw for credentials)
- msmtp: add Fastmail SMTP account
- neomutt: add fastmail account file, F2/F3 account switching macros
- vdirsyncer + khal: Fastmail CalDAV calendar sync
- zshrc: restore calsync alias

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

laptop/.config/isyncrc

@@ -22,4 +22,31 @@ Patterns * !Junk !Deleted
 Create Near
 Sync All
 Expunge Near
-SyncState *
+SyncState *
+
+##
+
+IMAPAccount fastmail
+Host imap.fastmail.com
+Port 993
+User rob@rharbaugh.com
+PassCmd "rbw get fastmail-app-password"
+TLSType IMAPS
+CertificateFile /etc/ssl/certs/ca-bundle.crt
+
+IMAPStore fastmail-remote
+Account fastmail
+
+MaildirStore fastmail-local
+SubFolders Verbatim
+Path ~/mail/fastmail/
+Inbox ~/mail/fastmail/Inbox/
+
+Channel fastmail
+Far :fastmail-remote:
+Near :fastmail-local:
+Patterns * !Spam
+Create Near
+Sync All
+Expunge Near
+SyncState *