Story 28: Show remaining test TODOs in the UI

Add TodoPanel that displays unchecked acceptance criteria from current
story files. Backend parses `- [ ]` lines from markdown, frontend
shows them in a panel with refresh. Includes 4 Rust unit tests,
3 Vitest tests, 3 Playwright E2E tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/GatePanel.test.tsx

@@ -9,8 +9,11 @@ const baseProps = {
 	gateStatusColor: "#aaa",
 	isGateLoading: false,
 	gateError: null,
+	coverageError: null,
 	lastGateRefresh: null,
 	onRefresh: vi.fn(),
+	onCollectCoverage: vi.fn(),
+	isCollectingCoverage: false,
 };
 
 describe("GatePanel", () => {
@@ -21,9 +24,7 @@ describe("GatePanel", () => {
 
 	it("shows loading message when isGateLoading is true", () => {
 		render(<GatePanel {...baseProps} isGateLoading={true} />);
-		expect(
-			screen.getByText("Loading workflow gates..."),
-		).toBeInTheDocument();
+		expect(screen.getByText("Loading workflow gates...")).toBeInTheDocument();
 	});
 
 	it("shows error with retry button", async () => {
@@ -64,13 +65,12 @@ describe("GatePanel", () => {
 					warning: null,
 					summary: { total: 5, passed: 5, failed: 0 },
 					missingCategories: [],
+					coverageReport: null,
 				}}
 				gateStatusLabel="Ready to accept"
 			/>,
 		);
-		expect(
-			screen.getByText(/5\/5 passing, 0 failing/),
-		).toBeInTheDocument();
+		expect(screen.getByText(/5\/5 passing, 0 failing/)).toBeInTheDocument();
 	});
 
 	it("shows missing categories", () => {
@@ -83,12 +83,11 @@ describe("GatePanel", () => {
 					warning: null,
 					summary: { total: 0, passed: 0, failed: 0 },
 					missingCategories: ["unit", "integration"],
+					coverageReport: null,
 				}}
 			/>,
 		);
-		expect(
-			screen.getByText("Missing: unit, integration"),
-		).toBeInTheDocument();
+		expect(screen.getByText("Missing: unit, integration")).toBeInTheDocument();
 	});
 
 	it("shows warning text", () => {
@@ -101,6 +100,7 @@ describe("GatePanel", () => {
 					warning: "Multiple tests failing — fix one at a time.",
 					summary: { total: 4, passed: 2, failed: 2 },
 					missingCategories: [],
+					coverageReport: null,
 				}}
 			/>,
 		);
@@ -119,12 +119,11 @@ describe("GatePanel", () => {
 					warning: null,
 					summary: { total: 2, passed: 1, failed: 1 },
 					missingCategories: [],
+					coverageReport: null,
 				}}
 			/>,
 		);
-		expect(
-			screen.getByText("No approved test plan."),
-		).toBeInTheDocument();
+		expect(screen.getByText("No approved test plan.")).toBeInTheDocument();
 		expect(screen.getByText("Tests are failing.")).toBeInTheDocument();
 	});
 
@@ -132,9 +131,7 @@ describe("GatePanel", () => {
 		const onRefresh = vi.fn();
 		render(<GatePanel {...baseProps} onRefresh={onRefresh} />);
 
-		await userEvent.click(
-			screen.getByRole("button", { name: "Refresh" }),
-		);
+		await userEvent.click(screen.getByRole("button", { name: "Refresh" }));
 		expect(onRefresh).toHaveBeenCalledOnce();
 	});