Add composing and sending: SMTP send + contacts + reply

Increment 5 — send.

- SmtpSender (Angus Mail; password/XOAUTH2) builds a MimeMessage and sends over
  SMTP/SMTPS. New OutgoingMessage + SmtpParams.
- MailConnectionFactory now resolves both IMAP and SMTP params (shared credential
  and token refresh); MailRepository.sendMessage.
- Compose screen wired to send: From account (a selector when there are several),
  To with device-contacts autocomplete (ContactsContract, runtime READ_CONTACTS),
  Cc, Subject, Body, with progress and error handling.
- Reply from the reader prefills To and a "Re:" subject (compose route gains optional
  to/subject args).
- Tests: GreenMail SmtpSender unit test. assemble/test/lint green; verified end-to-end
  on the Android 17 emulator — composed a message, sent it over SMTP to a local
  GreenMail server, and it round-tripped back into the inbox on re-sync.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/AndroidManifest.xml

@@ -4,6 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools">
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.READ_CONTACTS" />
 
     <application
         android:name=".LibreMailApplication"