BRO-001: render the hunk status/header line as a full-width banner

Now: DONE

The shared hunk renderer draws a hunk's status/header line (the {ts, verb, uri} metadata row — dog/HUNK.h, currently a plain <date>\t<verb>\t<uri> in text mode) without a clear visual band. Make it a proper banner: abbreviated time + URI on a pale-yellow, full-width, black-text line. This is the shared renderer used by every projector (log/status/grep/diff/commit/blame), so the fix lands once and benefits all. Prerequisite for BLAME-005.

Input

Context

A hunk is { ron60 ts; ron60 verb; u8cs uri; text/toks }; the status line is the ts/verb/uri row the renderer emits (HUNKu8sFeedText/ Color/Html in dog/HUNK.c, consumed by Bro).
Today the line has no distinct band — it reads as ordinary text and is easy to miss between content bodies.

Goals

The status/header line displays the time in abbreviated format (Fri12-style, the same formatter be head/log: already use) and the URI.
Style: pale-yellow background, spanning the FULL line width (not just the text), black text.

Constraints

Shared renderer (dog/HUNK.c HUNKu8sFeedColor for the TTY path; keep Text/Html modes coherent) — benefits all projectors, no per-producer code.
Reuse the existing abbreviated-date formatter (don't roll a new one).
Full-width fill must respect the terminal width bro already knows.

WIP

Design decisions

Open: does the banner keep the verb (the hunk's third field) alongside time + URI, or show only time + URI as stated? Default: keep verb (it's free data) unless it crowds the line.
Open: Text (non-TTY) and Html modes — match the banner intent (Html = pale-yellow row, already close per the ulog div) or leave Text plain.

TODOs

Banner in HUNKu8sFeedColor (hunk_feed_status_color) + bro's bro_render_ulog_title, via shared THEME_BANNER (dog/THEME.h).
Reused DOGutf8sFeedDate (the Fri12-style formatter).
bro (width-aware) pads the band to the terminal edge; verb kept; Text stays plain machine-grep; Html .ulog CSS made coherent.

Blockers and bummers

None. Unblocks BLAME-005 (per-commit-run hunk headers ride this banner).

Outcome

LANDED afc2bd48 — black-on-pale-yellow (48;5;230) full-width banner: abbrev date + verb + uri; shared THEME_BANNER; bro-padded width (no hardcode); HUNKTestStatusBanner across all 3 themes; 290/290 green.