docs: plan-era "v1", "Task N" and "Phase N" wording restated as facts (#6277)

The marker list behind the earlier server and web passes did not catch
"for v1", "Task 5", "Phase 2" or "today: Flutter". Those comments now say
what the code does.

Corrected: coverart said "both v1 providers" ship on. There are four
providers (MBCAA, TheAudioDB, Deezer, Last.fm), and Last.fm, which needs a
key, ships off.

Non-comment tokens unchanged against HEAD: 10 Go files, 7 TS/Svelte files.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/mailer/mailer.go

@@ -74,8 +74,8 @@ func (s *SMTPSender) Send(ctx context.Context, to, subject, textBody, htmlBody s
 	// We respect the use_tls flag: if true, we require STARTTLS via
 	// smtp.SendMail's default behavior (which negotiates STARTTLS when
 	// the server advertises it). For implicit-TLS (port 465 style),
-	// we'd need a custom dial — skip that complexity for v1 and rely on
-	// STARTTLS via port 587 (the default).
+	// we'd need a custom dial; instead this relies on STARTTLS via port
+	// 587 (the default).
 	dialCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
 	defer cancel()
 	_ = dialCtx // smtp.SendMail doesn't accept ctx; the timeout is enforced via Dialer below