Rework the conversation view to match the new dark-theme mockups:
- Subject bar gains a print button and an expand/collapse-all toggle (default
action expands all; collapsing leaves only the newest message open).
- Collapsed messages are compact single-line cards (40px avatar, colored sender
name, snippet, relative date) that overlap into a stack; alignment follows the
sort order (top edge for oldest-first, bottom edge for newest-first) and the
always-open newest card overlaps its neighbour in both orders.
- Expanded messages show sender+address (whole header row toggles collapse), a
detail disclosure (From/To/Cc/Subject/Date/Size), the message location
(Inbox/Sent), a read/unread circle (per-message flag toggle), a quick
Reply/Reply-all, and an Actions menu (reply/forward/print/delete). The
Reply/Reply all/Forward bar now sits inside the newest card above a divider.
- Message body: the quoted original is hidden by default with a "•••" toggle
injected after the "On … wrote:" attribution; the iframe now collapses-then-
measures so it shrinks back when the quote is hidden.
- Avatars use the sender's IMAP-account colour when the address matches one of
our accounts, else a stable per-sender hue; two initials for multi-word names.
- Brighter dark-theme border token; new print/expand-all/collapse-all icons.
Backend: add size_bytes to the message envelope (shown in message details).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
