fix(studio): centre tab labels and icons in the tab height

Also points the hovered-tab contrast pair at the lines that declare it.

packages/studio/src/components/dock/dock.css

@@ -130,10 +130,12 @@
     width 140ms ease-out;
 }
 
+/* Fills dockview's tab part, so the label and icon centre in the tab's full height. */
 .hf-dock-tab {
   display: flex;
   align-items: center;
   gap: 6px;
+  height: 100%;
 }
 
 .hf-dock .dv-inactive-tab .hf-dock-tab-icon,

packages/studio/src/components/dock/dockTabs.contract.test.ts

@@ -68,6 +68,12 @@ describe("dock panel strip contract", () => {
     expect(reduced).toContain(".hf-dock-tab-icon { animation: none; }");
   });
 
+  it("centres the tab's icon and label in the tab's full height", () => {
+    const tab = bodyOf(".hf-dock-tab");
+    expect(tab).toContain("height: 100%");
+    expect(tab).toContain("align-items: center");
+  });
+
   it("takes every colour from a token", () => {
     expect(dockCss).not.toMatch(/#[0-9a-f]{3,8}\b|rgba?\(|hsla?\(|oklch\(/i);
   });

scripts/contrast-pairs.json

@@ -300,8 +300,8 @@
           "role": "text",
           "minimum": 4.5,
           "sources": [
-            "packages/studio/src/components/dock/dock.css:97",
-            "packages/studio/src/components/dock/dock.css:99"
+            "packages/studio/src/components/dock/dock.css:101",
+            "packages/studio/src/components/dock/dock.css:103"
           ]
         }
       ]