Polish round: node-delete chrome + rename alignment

Owner polish dispatch (2026-09-23):

- Right-click no longer pins a node or opens the detail card: the
  canvas pointerdown/up handlers now gate on the primary button, so
  the context menu arrives alone.
- Node context menu: label is just "Delete" and the shell hugs its
  content (w-44 -> w-fit); the menu body keeps focus for arrow
  cycling but never shows the browser's default focus ring
  (outline-none on the MenuShell body - applies to every menu).
- Delete confirm: "Delete node?" title in CMU Serif, red
  (text-destructive); the node name sits below in JetBrains Mono
  inline-code; the Delete button carries the destructive treatment
  (border + tint, fill deepens on hover). Rest of the dialog stays
  neutral.
- Sidebar rename row: text and metadata stay at the idle row's x -
  the status spacer and the input's border/padding are gone; the
  underline is the only editing cue.

tests/session-context.test.tsx

@@ -40,6 +40,14 @@ describe("RenameRow — the inline rename surface", () => {
 		assert.ok(html.includes(`value="${chat.title}"`));
 		// the meta line rides along (row never changes height mid-edit)
 		assert.ok(html.includes("session-rename-row"));
+		// (owner, polish round) NOTHING MOVES: no status spacer, no input
+		// border/padding — the draft text sits at the idle row's title x,
+		// and the input is the ONLY shift-proof editing cue (underline).
+		assert.ok(!html.includes("w-3.5 shrink-0"), "no always-on spacer (idle rows have none)");
+		const input = html.split('data-testid="session-rename-input"')[1]?.split("/>")[0] ?? "";
+		assert.ok(input.includes("px-0"), "input carries no left padding");
+		assert.ok(input.includes("border-b"), "the underline is the editing cue");
+		assert.ok(!input.includes("bg-background"), "no filled field box — text stays put");
 	});
 });