DiagnosticsCollector now includes one "<provider> (<authType>)" entry per account (the count is the
list size) in DebugReport.accounts, alongside the existing settings + recent-log capture. The provider
is a coarse bucket derived from the IMAP host (Gmail/Yahoo/iCloud/Outlook/AOL/Other) — never the raw
host or email — so no PII leaks; a custom domain buckets to "Other". Accounts are cached like settings
so crash reports (built on the crashing thread) include the last-known snapshot; accounts live in the
non-auth AccountDatabase, so reading them never blocks on the encrypted cache.
Recent device/app logs were already captured (RingLogBuffer) and serialize as the report's "logs".
Closes#235
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>