fix(web): make plugin detail page scrollable (#7070)

Author: lefarcen

apps/web/src/styles/home/plugin-marketplace-demo.css

@@ -888,7 +888,14 @@
 }
 
 .plugin-suite-detail {
-  padding-top: 18px;
+  height: 100%;
+  min-height: 0;
+  overflow-x: hidden;
+  overflow-y: auto;
+  overscroll-behavior: contain;
+  scrollbar-gutter: stable;
+  scrollbar-width: thin;
+  padding: 18px 0 72px;
 }
 
 .plugin-suite-detail__topbar {

apps/web/tests/styles/plugin-detail-scroll.test.ts

@@ -0,0 +1,23 @@
+import postcss, { type Declaration, type Rule } from 'postcss';
+import { describe, expect, it } from 'vitest';
+import { readExpandedIndexCss } from '../helpers/read-expanded-css';
+
+describe('plugin detail page scrolling', () => {
+  it('owns vertical overflow inside the fixed-height workspace shell', () => {
+    const root = postcss.parse(readExpandedIndexCss(), { from: 'src/index.css' });
+    const rule = root.nodes.find(
+      (node): node is Rule => node.type === 'rule' && node.selector === '.plugin-suite-detail',
+    );
+    const declarations = new Map(
+      rule?.nodes
+        .filter((node): node is Declaration => node.type === 'decl')
+        .map((declaration) => [declaration.prop, declaration.value]),
+    );
+
+    expect(declarations.get('height')).toBe('100%');
+    expect(declarations.get('min-height')).toBe('0');
+    expect(declarations.get('overflow-x')).toBe('hidden');
+    expect(declarations.get('overflow-y')).toBe('auto');
+    expect(declarations.get('scrollbar-gutter')).toBe('stable');
+  });
+});