fix(compile): bump frontend axios timeout 180s → 600s for ESP-IDF builds

Cold ESP-IDF builds (esp32, esp32-c3, esp32-cam) routinely take 5-10
minutes the first time a project is compiled. The 180s axios timeout
on POST /api/compile/ was cutting the connection long before the
backend finished, surfacing as the misleading 'No response from
server. Is the backend running on port 8001?' error.

Bumping the client timeout to 600s aligns with the nginx
proxy_read_timeout (also 600s) so the chain end-to-end is consistent.

Arduino sketches still compile in seconds — the timeout is an upper
bound, not a delay.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/services/compilation.ts

@@ -35,7 +35,7 @@ export async function compileCode(
     const response = await axios.post<CompileResult>(
       `${API_BASE}/compile/`,
       { files, board_fqbn: board, project_id: projectId ?? null },
-      { withCredentials: true, timeout: 180000 },
+      { withCredentials: true, timeout: 600000 },
     );
 
     console.log('Compilation response status:', response.status);