Add markdown rendering with syntax highlighting and copy buttons

- Implement markdown parser using marked with Shiki syntax highlighting
- Add CodeBlockInline component for tool call outputs with syntax highlighting
- Add Markdown component for assistant message text with code blocks
- Add ThemeProvider for light/dark mode support
- Add copy buttons to all code blocks (markdown and tool calls)
- Support 20+ languages: TypeScript, JavaScript, Python, Bash, JSON, HTML, CSS, C++, Java, C, C#, Rust, Go, PHP, Ruby, Swift, Kotlin, and more
- Auto-detect language from file extensions in tool call outputs
- Apply consistent styling for code blocks across the application
- Fix whitespace handling in markdown-rendered text
- Add language labels to all code blocks

src/main.tsx

@@ -1,5 +1,6 @@
 import { render } from "solid-js/web"
 import App from "./App"
+import { ThemeProvider } from "./lib/theme"
 import "./index.css"
 
 const root = document.getElementById("root")
@@ -8,4 +9,11 @@ if (!root) {
   throw new Error("Root element not found")
 }
 
-render(() => <App />, root)
+render(
+  () => (
+    <ThemeProvider>
+      <App />
+    </ThemeProvider>
+  ),
+  root,
+)