- Add imapServerId column (schema v24) to Drafts table; guard migration
with from>=4 since createTable already uses latest schema
- Extend SavedDraft model and DraftRepository interface with syncDrafts()
- Implement syncDrafts in DraftRepositoryImpl: create/select Drafts
folder, upload local-only drafts via APPEND, import server drafts not
tracked locally
- Wire AccountRepository and ImapConnectFn into DraftRepositoryImpl via
draftRepositoryProvider
- Call syncDrafts from AccountSyncManager._AccountSync._sync() so each
IMAP sync cycle also syncs the Drafts folder
- Add syncDrafts stub to FakeDraftRepository; update unit test
constructor calls with _StubAccounts
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>