Inline images in rich HTML emails (embedded via Content-ID and
<img src="cid:...">, e.g. USPS Informed Delivery digests) were listed
under Attachments with a download button and never rendered in the body.
Two bugs combined; both are fixed here.
1. Misclassification: ImapClient classified any part with a filename as
an attachment, sweeping inline images (which carry a filename AND a
Content-ID under Content-Disposition: inline) into the list. A part is
now a downloadable attachment only when its disposition is attachment,
or it has a filename but no Content-ID; an inline image is collected
separately and excluded from the displayed list (AttachmentDao filters
contentId IS NULL). The Content-ID is read via MimePart.getContentID()
so it resolves from IMAP BODYSTRUCTURE rather than a per-part header
fetch that Angus leaves unpopulated.
2. No rendering path: HtmlBody's WebViewClient now overrides
shouldInterceptRequest to resolve cid:<id> to the matching part's
bytes (backing the CSP's existing cid: allowance). Content-ID is
threaded end-to-end through AttachmentPart, Attachment,
AttachmentEntity, and MailRepository.inlineImages(); ReaderViewModel
surfaces the cid->bytes map to the WebView.
Schema: adds attachments.contentId (v16 -> v17, MIGRATION_16_17).
Tests: MIME-part classification (inline+cid excluded, real/disposition/
filename-only kept), a GreenMail multipart/related round-trip, the
cid->bytes resolver, repository inlineImages(), the DAO display filter,
and the v16->v17 migration.
Closes#133
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>