#303: the reader's Reply now routes through MailRepository.buildReplyDraft
(quotes the original into a <blockquote>, bakes the signature, prefixes Re:/Fwd:
without double-prefixing) and opens compose on the built draft via
ReaderEvent.OpenCompose — the same high-fidelity path the mailbox uses — instead
of a bare compose prefill with an empty body. Adds Reply-All and Forward via an
app-bar overflow menu.
#304: SignatureEditViewModel.save, ReportReviewViewModel.submit,
AccountSettingsViewModel.removeAccount, and ProblemReportsViewModel.createManualReport
now flip a busy/saving flag synchronously before the first suspension and gate
their buttons, so a rapid double-tap can't create duplicate signatures/reports,
enqueue two uploads, or over-pop the back stack.
Closes#303Closes#304
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>