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/phase-divider.tsx

@@ -34,12 +34,15 @@ const CHIP_LABEL: Record<Phase3, string> = {
 /** The header chip: the phase label, monochrome — label-only by design
  *  (see the component note: the pill's curve suits text, not glyphs). */
 export function PhaseChip({ phase }: { phase: Phase3 }) {
+	// Pure decoration (owner ask, 2026-09-17): no tooltip, not selectable,
+	// not interactive in any way — no pointer events at all, so it is part
+	// of the drag surface instead of a carved-out target.
 	return (
 		<span
 			data-testid="phase-chip"
 			data-phase={phase}
-			title={`Session phase: ${CHIP_LABEL[phase]}`}
-			className="lh-no-drag flex shrink-0 items-center rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground"
+			aria-hidden="true"
+			className="pointer-events-none flex shrink-0 select-none items-center rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground"
 		>
 			{CHIP_LABEL[phase]}
 		</span>