feat(view): paint the whole card in one delegate

Replaces SubjectDelegate. The tag chips come home from the view: the strip was
painted there only because a delegate cannot paint outside its column and the
strip spanned all five, and with one column there is nothing to span.

RowStyleDelegate is inherited rather than dropped. Its job survives the
redesign: Qt resolves ForegroundRole into the palette's Text roles and prefers
those over HighlightedText, so the read/unread dimming would win on a selected
row and land as grey on the highlight. What it loses is the rest of its body,
which aligned cells against a text band and centred two marker columns; both
described a grid that no longer exists.

A reply's Re: prefix is stripped here. Every reply repeating the thread's
subject is the visual signature of a table of records, which is the thing item
53 is about.

The account chip becomes a bar down the card's left edge, and the reply spines
inherit its colour, so an expanded thread is bounded by one accent from its root
to its last reply without a second line in the gutter. Neither uses the raw
account colour: that colour is chosen to be a chip's fill with legible text on
top, and the same value as a thin line has to be followable down an expansion
without competing with the senders, so it is blended toward the palette's Base
by the weight threadLineColour() already uses. A reply resolves its THREAD's
colour by walking to the root, since AccountColourRole is empty on a message
row and a neutral spine under an accented root would break the continuous edge.

The build is red at this commit; the view and window still name the old
delegate.

0 files changed, 0 insertions, 0 deletions