fix(ui): #542 landing fixes

Follow the keyboard: the menu's cap now uses var(--app-height, 100dvh)
instead of 100dvh. The viewport meta has no interactive-widget, so dvh does
not shrink for an on-screen keyboard, while MobileDetection always sets
--app-height to the visual viewport height and KeyboardHandler keeps it there
while the keyboard is up (body and .app already size the same way).

Subtract both safe areas from the cap: in the iPhone home-screen app the
phone header grows by the top inset and the toolbar sits above the bottom
inset, so without them the top of a full menu slid under the fixed header.

Add overflow-x: hidden. overflow-y: auto computes overflow-x to auto, so a
long nowrap custom-endpoint label showed a horizontal scrollbar that
touch-action: pan-y cannot pan (the same trap the file documents for
.run-mode-history).

Raise the toolbar while the Run menu is open, by adding
.toolbar:has(.run-mode-menu.active) to the existing popover raise rule. The
menu is trapped in the toolbar's stacking context, so on a touch device the
keyboard accessory bar (z 51) and the visible CJK input (z 52) covered its
last rows even when scrolled to the end. This follows the rule the case
settings popover and case combobox already use.

Reword the rule's comment: it claimed dvh follows the keyboard and that the
vh line is a fallback, and neither is true (a declaration carrying var() is
never dropped at parse time). The new text has no braces and no max-height
text, which the gate test's rule() slicer depends on.

Pin the fixes in the gate test (the --app-height and safe-area terms,
overflow-x: hidden, the toolbar raise) and retitle the cap test so it no
longer names dvh as the mechanism. The test now strips CSS comments before
reading the rule, since the rule's own comment names overflow-y: auto and
touch-action: pan-y and would otherwise keep those assertions green after the
declarations were deleted (checked by deleting them: the test now fails).

Drop .changeset/run-menu-scroll.md: it repeated the false dvh claim, and the
release writes one consolidated changeset at COM.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

test/run-mode-menu-scroll.test.ts

@@ -8,7 +8,12 @@
 import { readFileSync } from 'node:fs';
 import { describe, expect, it } from 'vitest';
 
-const css = readFileSync(new URL('../src/web/public/styles.css', import.meta.url), 'utf8');
+// Comments stripped: the rule's own comment names `overflow-y: auto` and `touch-action: pan-y`,
+// which would otherwise satisfy the assertions below after the declarations were deleted.
+const css = readFileSync(new URL('../src/web/public/styles.css', import.meta.url), 'utf8').replace(
+  /\/\*[\s\S]*?\*\//g,
+  ''
+);
 
 /** The declaration block of the FIRST rule whose selector is exactly `selector`. */
 function rule(selector: string): string {
@@ -27,17 +32,32 @@ describe('Run dropdown scrolls when it is taller than the room above the toolbar
     expect(menu).toMatch(/touch-action:\s*pan-y/);
   });
 
-  it('is capped to the space between the header and the toolbar, in dvh with a vh fallback', () => {
+  it('is capped to the space between the header and the toolbar, following --app-height and the safe areas', () => {
     const caps = [...menu.matchAll(/max-height:\s*([^;]+);/g)].map((m) => m[1]);
     expect(caps).toHaveLength(2);
     expect(caps[0]).toContain('100vh');
     expect(caps[1]).toContain('100dvh');
+    // dvh does not shrink for the on-screen keyboard; --app-height (the visual viewport) does.
+    expect(caps[1]).toContain('var(--app-height');
     for (const cap of caps) {
       expect(cap).toContain('var(--header-height)');
       expect(cap).toContain('var(--toolbar-height)');
+      // The phone header and toolbar grow by the safe areas in the iPhone home-screen app.
+      expect(cap).toContain('var(--safe-area-top)');
+      expect(cap).toContain('var(--safe-area-bottom)');
     }
   });
 
+  it('never scrolls sideways (a long custom-endpoint label must not add a horizontal scrollbar)', () => {
+    expect(menu).toMatch(/overflow-x:\s*hidden/);
+  });
+
+  it('raises the toolbar while the menu is open, so its last rows clear the keyboard bar and the CJK input', () => {
+    // The menu is trapped in the toolbar's stacking context (backdrop-filter), so only the
+    // toolbar's own z-index can lift it over the accessory bar (z 51) and #cjkInput (z 52).
+    expect(css).toMatch(/\.toolbar:has\(\.run-mode-menu\.active\)[\s\S]*?\{\s*z-index:\s*100;/);
+  });
+
   it('does not let scrolling children (history, saved URLs) be squashed to nothing', () => {
     expect(rule('.run-mode-menu > *')).toMatch(/flex-shrink:\s*0/);
   });