feat(web): polish master chat with model selector, params config, and empty state (#519)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/web/src/components/chat/Chat.test.tsx

@@ -43,6 +43,15 @@ vi.mock("./ChatInput", () => ({
       Send
     </button>
   ),
+  DEFAULT_TEMPERATURE: 0.7,
+  DEFAULT_MAX_TOKENS: 4096,
+  DEFAULT_MODEL: "llama3.2",
+  AVAILABLE_MODELS: [
+    { id: "llama3.2", label: "Llama 3.2" },
+    { id: "claude-3.5-sonnet", label: "Claude 3.5 Sonnet" },
+    { id: "gpt-4o", label: "GPT-4o" },
+    { id: "deepseek-r1", label: "DeepSeek R1" },
+  ],
 }));
 
 const mockUseAuth = authModule.useAuth as MockedFunction<typeof authModule.useAuth>;