fix(ui): vendor dropdown polish — authored arrow-cap with open/closed flip, downward popup, left-aligned rows

Three gate findings, each settled by authored data rather than
invention: the button face is retail's two-piece assembly and the
17x19 arrow-cap 0x1000034E now renders with its authored
Normal(closed)/Highlight(open) states; the popup direction is an
AUTHORED attribute (UIElement_Menu::Open pc:120210-120252 — bool
attr 5, chat authors upward=true, the vendor menu authors nothing and
defaults downward), so both menus are now byte-faithful with no
special case; and the 19/20px text indents were chat-specific
checkbox/LED clearances the vendor rows don't author — measured
against the live retail font, "Spell Components" overflowed by 11px
and now fits with 8px to spare. Chat's menu defaults are bit-identical
and its tests untouched.

AP-161's arrow-cap note closes. #351 files the pre-existing FarLoad
Debug flake (three sightings today, never in clean-room Release).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -24,6 +24,14 @@ What does NOT go here:
 - Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
 - Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
 
+## #351 — LandblockBuildOriginTests.FarLoad_StripsEnvCellsAndPhysics flake (Debug, load-sensitive)
+
+**Status:** OPEN (filed 2026-08-08). Seen three times today in Debug runs
+under parallel-agent load (5.4 implementer, Slice 6 corrections, dropdown
+polish), each time proven pre-existing by re-running against the pristine
+base commit; never reproduces in clean-room Release. An async streaming
+timing assumption most likely; deflake when it next blocks a verdict.
+
 ## #350 — Render-shadow ledger overflow after 2h42m: lifetime int counters in a never-reset accumulator
 
 **Status:** FIXED IN TREE 2026-08-08 (pending clean-room + landing).