graph: import + cost ride the chains home's TOP BAR (release polish 2.1)

Owner refinement on the chains home: the floating top-right chrome row
sat ON TOP of the propositions table — covering content reads badly.
The two survivors (Import notes — always, the entry-point law; the
cost pill when any run exists) now ride the shared TopBar's right
cluster, left of the search input, carved out of the drag band with
lh-no-drag — consistent with the graph view, where they already live in
the top band.

ChainTableBody gains topBarExtra?: React.ReactNode (absent on the
overlay — nothing changes there); ChainsHome's floating chrome row is
deleted; the empty state keeps its own centered import button.

Parked for the next design pass (owner, this round): (1) the pick flow
reads messy — checkboxes show by default, so the pill's select mode is
near-invisible and after Done the Clear/Delete bar + the practice pill
coexist with two Clear buttons; the original vision was checkboxes
appear ONLY when picking. (2) the composer's clearance band has no
outline — the docked area needs a visual edge.

1415 tests (new pin: topBarExtra renders in the bar with the drag
carve; overlay variant injects nothing); tsc, lint, build green.

tests/render-chain-table.test.tsx

@@ -82,6 +82,7 @@ const BASE = {
 	onGenerate: () => {},
 	onDelete: () => {},
 	onClose: () => {},
+	topBarExtra: undefined as React.ReactNode,
 };
 
 function render(props: Partial<typeof BASE> = {}) {
@@ -96,6 +97,14 @@ describe("ChainTableBody — the HOME variant (graph rendering off, 2026-10-06)"
 		assert.ok(html.includes("chain"), "the counts stay");
 		assert.ok(html.includes("lh-drag"), "the window-drag band stays (same bar as every surface)");
 	});
+
+	it("topBarExtra injects into the bar's right cluster — import + cost ride the TOP BAR (owner, 2026-10-06)", () => {
+		const html = render({ onClose: undefined, topBarExtra: React.createElement("b", { "data-testid": "tbx" }, "X") });
+		assert.ok(html.includes('data-testid="tbx"'), "the extra renders inside the bar");
+		assert.ok(html.includes("lh-no-drag"), "the cluster carves out of the drag band");
+		const overlay = render();
+		assert.ok(!overlay.includes('data-testid="tbx"'), "absent by default — the overlay variant injects nothing");
+	});
 });
 
 describe("ChainTableBody — clusters (the outermost layer)", () => {