fix: top-bar polish — lights on the pill line, rename escape hitbox, inert phase pill, chrome carve-outs

Traffic lights (owner report: 'way too low, not aligned with the phase pill'):
measured in the running app — circles centered at 30.75pt vs the pill box's
29.25pt (band 0-59.5, pill box 19-39.5, pill ink 28.75; uppercase glyphs sit
high). trafficLightPosition y 24 -> 22.5 lands the circle centers at 29.25,
exactly on the pill. Owner confirmed aligned after this change.

Rename escape hitbox (owner report): entering rename was already width-of-
title only, but the editing input spanned flex-1 so clicking the rest of the
bar stayed inside the input. The input is now shrink-to-fit
([field-sizing:content], min 8ch / max 70%) and any mousedown outside the
input blurs it, running the existing onBlur commit path; the header drops
lh-drag while renaming so the drag region cannot eat the escape click.
Verified: click-away commits (exactly one PUT), Escape discards, Enter
commits.

Phase pill is pure decoration (owner report: 'should not be interactable
in any way'): no tooltip, pointer-events-none, select-none — part of the
drag surface instead of a carved-out target.

Graph chrome was unclickable in Electron (owner report): home.tsx's
floating drag strip underlays the z-10 controls row, and Electron's
app-region mask ignores z-index, so the region ate their clicks (plain
browser unaffected — DOM hit-testing is fine). lh-no-drag carve-outs on
the chrome row and the node detail card (it is placed imperatively
anywhere, including the top strip).

LhMark home link now mirrors the ghost toggle: same size-9 chip geometry
and hover:bg-accent treatment.

components/sidebar.tsx

@@ -264,10 +264,12 @@ function SessionsSidebar() {
 					    home link, still vertically centered by the band's items-center.
 					    The 92px .lh-lights-gutter keeps it clear of the traffic lights
 					    with the lights' own edge-inset as the gap. */}
+					{/* Hover mirrors the ghost toggle buttons (owner ask, 2026-09-17):
+					    same size-9 chip geometry, same hover:bg-accent treatment. */}
 					<Link
 						href="/"
 						aria-label="Home"
-						className="lh-no-drag shrink-0 rounded-md transition-opacity hover:opacity-80"
+						className="lh-no-drag flex size-9 shrink-0 items-center justify-center rounded-md transition-colors hover:bg-accent hover:text-accent-foreground dark:hover:bg-accent/50"
 					>
 						<LhMark className="size-6" />
 					</Link>