fix(canvas/Toolbar): help button always opens — no double-click close bug

The help button's onClick used setHelpOpen((open) => !open) (toggle).
Combined with the window.pointerdown handler that closes on outside-click,
clicking outside then clicking the help button would: pointerdown outside
(close) → click on button (!false = true → open) → pointerdown ON button
(contains=true, no close) → BUT the next interaction would have stale
toggle state causing a double-close on the following click.

Fix: button onClick always calls setHelpOpen(true) — the pointerdown
outside handler owns the close path; the button only opens.

Also add 2 tests: pointer-down-outside closes, and re-open works after
outside click (regression for the double-click bug).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

canvas/src/components/Toolbar.tsx

@@ -314,7 +314,7 @@ export function Toolbar() {
       <div ref={helpRef} className="relative">
         <button
           type="button"
-          onClick={() => setHelpOpen((open) => !open)}
+          onClick={() => setHelpOpen(true)}
           className="flex items-center justify-center w-7 h-7 bg-surface-card hover:bg-surface-card/70 border border-line rounded-lg transition-colors text-ink-mid hover:text-ink focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/40"
           aria-expanded={helpOpen}
           aria-label="Open shortcuts and tips"

canvas/src/components/__tests__/Toolbar.test.tsx

@@ -255,6 +255,32 @@ describe("Toolbar — Help popover", () => {
     fireEvent.click(closeBtn);
     expect(screen.queryByRole("dialog")).toBeNull();
   });
+
+  it("closes when pointer is pressed outside the help popover", () => {
+    render(<Toolbar />);
+    const helpBtn = screen.getByRole("button", { name: /open shortcuts and tips/i });
+    fireEvent.click(helpBtn);
+    expect(screen.getByRole("dialog")).toBeTruthy();
+    // Simulate pointerdown outside the help popover (not on the help button)
+    fireEvent.pointerDown(document.body);
+    expect(screen.queryByRole("dialog")).toBeNull();
+  });
+
+  it("opens on click even after a previous pointer-outside close", () => {
+    // Regression: clicking outside closed the popover AND toggled the button
+    // state, so the next click on the button would close it again.
+    // The fix makes the button always open (never toggle) so re-opening works.
+    render(<Toolbar />);
+    const helpBtn = screen.getByRole("button", { name: /open shortcuts and tips/i });
+    fireEvent.click(helpBtn);
+    expect(screen.getByRole("dialog")).toBeTruthy();
+    // Click outside (pointerdown on body, not on help button)
+    fireEvent.pointerDown(document.body);
+    expect(screen.queryByRole("dialog")).toBeNull();
+    // Click the help button again — must re-open, not double-close
+    fireEvent.click(helpBtn);
+    expect(screen.getByRole("dialog")).toBeTruthy();
+  });
 });
 
 describe("Toolbar — A2A edges toggle", () => {