feat: add models management and usage history components

- Introduced RequestContentDialog for displaying request content details.
- Added UsageBarChart for visualizing token usage data.
- Implemented UsageHistorySection to manage and display usage history with filtering and pagination.
- Created provider-types for managing provider-related types.
- Developed ModelsPage to encapsulate models configuration, providers, and usage history.
- Defined usage-history types and utility functions for managing usage data.
- Updated routing to include models page and redirect agents to models.
- Refactored chat store to integrate models instead of agents.
- Established models store for managing model-related state and data fetching.

src/pages/Models/components/RequestContentDialog.tsx

@@ -0,0 +1,44 @@
+import DialogSurface from './DialogSurface';
+import type { UsageHistoryEntry } from '../usage-history';
+
+type RequestContentDialogProps = {
+  open: boolean;
+  entry: UsageHistoryEntry | null;
+  onClose: () => void;
+};
+
+function formatUsageTimestamp(timestamp?: string): string {
+  if (!timestamp) return '';
+
+  const date = new Date(timestamp);
+  if (Number.isNaN(date.getTime())) return timestamp;
+
+  return new Intl.DateTimeFormat(undefined, {
+    month: 'short',
+    day: 'numeric',
+    hour: '2-digit',
+    minute: '2-digit',
+  }).format(date);
+}
+
+export default function RequestContentDialog({
+  open,
+  entry,
+  onClose,
+}: RequestContentDialogProps) {
+  return (
+    <DialogSurface
+      open={open}
+      onClose={onClose}
+      title="Request Content"
+      subtitle={entry ? `${entry.model || 'Unknown Model'} • ${formatUsageTimestamp(entry.timestamp)}` : undefined}
+      widthClassName="max-w-[800px]"
+    >
+      <div className="max-h-[60vh] overflow-y-auto rounded-[16px] border border-black/6 bg-white p-5 shadow-sm dark:border-white/8 dark:bg-[#1f1f22]">
+        <pre className="whitespace-pre-wrap break-words font-mono text-[13px] leading-relaxed text-[#171717] dark:text-[#f3f4f6]">
+          {entry?.content || ''}
+        </pre>
+      </div>
+    </DialogSurface>
+  );
+}