Feat: Replace pagination bar with numbered page buttons and chevron controls

Adds « ‹ [1][2][3][4] › » navigation to the library. Page window
slides to keep the current page in view. Prev/next/first/last controls
are always rendered but disabled at their respective bounds. Also wires
up karmaConfig in angular.json so FirefoxHeadless is used for tests.

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

ui/karma.conf.js

@@ -14,7 +14,13 @@ module.exports = function (config) {
     jasmineHtmlReporter: { suppressAll: true },
     coverageReporter: { dir: require('path').join(__dirname, './coverage/reactbin-ui'), subdir: '.', reporters: [{ type: 'html' }, { type: 'text-summary' }] },
     reporters: ['progress', 'kjhtml'],
-    browsers: ['Chrome'],
+    customLaunchers: {
+      FirefoxHeadless: {
+        base: 'Firefox',
+        flags: ['--headless'],
+      },
+    },
+    browsers: ['FirefoxHeadless'],
     restartOnFileChange: true,
   });
 };