feat(web): port chat UI — model selector, keybindings, thinking display, styled header

apps/web/src/lib/types.ts

@@ -15,10 +15,41 @@ export interface Message {
   conversationId: string;
   role: 'user' | 'assistant' | 'system';
   content: string;
+  thinking?: string;
+  model?: string;
+  provider?: string;
+  promptTokens?: number;
+  completionTokens?: number;
+  totalTokens?: number;
   metadata?: Record<string, unknown>;
   createdAt: string;
 }
 
+/** Model definition returned by provider APIs. */
+export interface ModelInfo {
+  id: string;
+  provider: string;
+  name: string;
+  reasoning: boolean;
+  contextWindow: number;
+  maxTokens: number;
+  inputTypes: Array<'text' | 'image'>;
+  cost: {
+    input: number;
+    output: number;
+    cacheRead: number;
+    cacheWrite: number;
+  };
+}
+
+/** Provider with associated models. */
+export interface ProviderInfo {
+  id: string;
+  name: string;
+  available: boolean;
+  models: ModelInfo[];
+}
+
 /** Task statuses. */
 export type TaskStatus = 'not-started' | 'in-progress' | 'blocked' | 'done' | 'cancelled';