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/.zshrc

@@ -20,6 +20,7 @@ export PATH="$HOME/.local/bin:$HOME/.cargo/bin:$HOME/go/bin:$HOME/.local/bin:$PA
 # Aliases
 alias e="emacsclient -t -a \"\""
 alias mbsync="mbsync -a"
+alias calsync="vdirsyncer sync"
 alias c="clear"
 alias cat="bat --paging=never --style=plain"
 alias cp="cp -riv"