Phase 5: reply drafts — template/LLM draft, edit, SMTP send (AUD-71)

Implements Phase 5 of AGENTS.md §11 (FR-8, FR-15):

- Message detail pane (GET /partials/message) with body, recommended
  action, reply identity, template picker, editable draft, and history.
- internal/reply: OmniRoute (OpenAI-compatible) chat client and a
  template-based draft generator. All non-JEV models go through
  OmniRoute (§10).
- internal/mailops: SMTP send over smtp.gmail.com:587 with STARTTLS and
  the app password, forcing IPv4 (§9); FR-15 reply identity (send as the
  arrived-at X-Pm-Original-To address, else "Sam Rolfe"); threading via
  In-Reply-To/References; -check-smtp safe verification; and a
  [Gmail]/Sent Mail thread check.
- Migration v5 stores messages.message_id_header and drafts.sent_at;
  mailfetch parses Message-ID.
- Send is user-triggered only: CSRF + UI confirm + confirm=yes guard,
  no auto-send, duplicate-send refused. A sent reply files the original
  under Replied-to/<address> and logs every step (FR-13).
- Tests for reply, mailops SMTP/identity/thread check, store drafts and
  migration v5, and the server draft/edit/send guards.
- docs/phase5-replies.md, README, .env.example, docker-compose updated.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

internal/mailops/mailops_test.go

@@ -45,6 +45,10 @@ func (f *fakeConn) SearchGmailID(id string) ([]uint32, error) {
 	f.searched = append(f.searched, id)
 	return f.searchUIDs, f.searchErr
 }
+func (f *fakeConn) SearchGmailThreadID(id string) ([]uint32, error) {
+	f.searched = append(f.searched, "thrid:"+id)
+	return f.searchUIDs, f.searchErr
+}
 func (f *fakeConn) Logout() error { f.loggedOut = true; return nil }
 
 func configured() *config.Config {
@@ -54,6 +58,8 @@ func configured() *config.Config {
 		IMAPPort:         config.DefaultIMAPPort,
 		GmailUser:        "user@example.test",
 		GmailAppPassword: "app-password",
+		SMTPHost:         config.DefaultSMTPHost,
+		SMTPPort:         config.DefaultSMTPPort,
 	}
 }