Align the title-bar surface audit with the zoom rework

'Scale desktop title bar with page zoom' (833d2f1) changed the CSS contract
in two ways its audit test still pinned the old shape of: the lane vars gained
a max() floor around the platform env() terms so page zoom cannot shrink the
lane below the OS-drawn lights, and the control square became fixed px — CSS px
already scale under zoom — leaving only the centering offset derived from the
lane height. The test required the bare env() prefix and calc() on all three
control vars, so it failed the commit that implemented its own regression
comment.

Pins now assert the env() term inside the clamp (still platform-derived, the
test's actual intent) and split the control vars: offset must stay computed,
size and icon are explicit constants.

Author: Sg312

apps/sim/app/_shell/desktop-title-bar-surfaces.test.ts

@@ -86,22 +86,28 @@ describe('desktop title-bar surface audit', () => {
   // Regression: a px clearance shrinks under page zoom while the OS-drawn lights
   // do not, so they end up drawn over the sidebar toggle.
   it('reserves the traffic-light lane from the platform, not hardcoded pixels', () => {
-    expect(globalStyles).toContain('--desktop-title-bar-height: env(titlebar-area-height,')
-    expect(globalStyles).toContain('--desktop-title-bar-inset-x: env(titlebar-area-x,')
+    // The env() term is the platform-derived part; the max() floor keeps the
+    // lane from collapsing below the OS-drawn lights under page zoom.
+    expect(globalStyles).toContain('--desktop-title-bar-height: max(env(titlebar-area-height,')
+    expect(globalStyles).toContain('--desktop-title-bar-inset-x: max(env(titlebar-area-x,')
 
     // Scoped to the desktop block: the `:root` zeros are the deliberate
     // no-lane case, so only the overrides must stay derived.
     const insetBlock = globalStyles.match(
       /html\[data-sim-desktop-title-bar="inset"\]\s*\{([^}]*)\}/
     )?.[1]
     expect(insetBlock).toBeTypeOf('string')
+    // The zoom rework split the lane from the control: the lane stays
+    // platform-derived (clamped env() above), while the control is a fixed
+    // square — CSS px already scale under page zoom, so only the centering
+    // offset must remain computed from the lane height.
+    expect(insetBlock).toMatch(/--desktop-title-bar-control-offset: calc\(/)
+    expect(insetBlock).not.toMatch(/--desktop-title-bar-control-offset:\s*[\d.]+px/)
     for (const name of [
       '--desktop-title-bar-control-size',
       '--desktop-title-bar-control-icon-size',
-      '--desktop-title-bar-control-offset',
     ]) {
-      expect(insetBlock).toMatch(new RegExp(`${name}: calc\\(`))
-      expect(insetBlock).not.toMatch(new RegExp(`${name}:\\s*[\\d.]+px`))
+      expect(insetBlock).toMatch(new RegExp(`${name}:\\s*[\\d.]+px`))
     }
 
     // Both lane consumers read those vars; a literal in either is the bug.