fix(ui): align Skills, Access Groups and Budgets page spacing with Teams

Teams sets its list-view padding with `p-8` and its header-to-content
rhythm with a `gap-6` Tabs root. These three pages each drifted from that
in one of two ways: Skills carried `m-8 p-2`, and Access Groups and
Budgets carried `p-6 px-12`, so horizontal padding ran 48px against
Teams' 32px.

Skills also nested its own `overflow-y-auto` inside the dashboard
layout's scrolling `<main>`, which is why it scrolled independently of
every other page. Dropping it also drops `mx-auto` and `flex-auto`, both
inert here since there is no max-width to center against and the parent
`<main>` is a block.

Guardrails, Agents, Prompts, Projects, and the two detail pages share the
same two deviations and are left alone. There is no shared page shell to
fix them all at once, and building one reaches 8+ files.

ui/litellm-dashboard/src/app/(dashboard)/access-groups/_components/AccessGroupsPage.tsx

@@ -59,8 +59,8 @@ export function AccessGroupsPage() {
   }
 
   return (
-    <div className="p-6 px-12">
-      <div className="mb-4">
+    <div className="p-8">
+      <div className="mb-6">
         <LegacyPageHeader
           title="Access Groups"
           subtitle="Manage resource permissions for your organization"

ui/litellm-dashboard/src/app/(dashboard)/budgets/_components/budget_panel.tsx

@@ -79,7 +79,7 @@ const BudgetPanel: React.FC<BudgetSettingsPageProps> = ({ accessToken }) => {
   };
 
   return (
-    <div className="flex h-full flex-col gap-4 p-6 px-12">
+    <div className="flex h-full flex-col gap-6 p-8">
       <LegacyPageHeader
         icon={<Wallet className="size-5" />}
         title="Budgets"

ui/litellm-dashboard/src/app/(dashboard)/skills/_components/ClaudeCodePluginsPanel.tsx

@@ -78,7 +78,7 @@ const ClaudeCodePluginsPanel: React.FC<ClaudeCodePluginsPanelProps> = ({ accessT
   };
 
   return (
-    <div className="w-full mx-auto flex-auto overflow-y-auto m-8 p-2">
+    <div className="p-8">
       {selectedSkill ? (
         <SkillDetail
           skill={selectedSkill}