fix(api): clean unused imports and prefer-const in ask-ai route to satisfy ESLint

app/api/ask-ai/route.ts

@@ -6,7 +6,7 @@ import { headers } from "next/headers";
 import { InferenceClient } from "@huggingface/inference";
 
 import { MODELS, PROVIDERS } from "@/lib/providers";
-import { DEFAULT_MODEL as DEFAULT_MODEL_FLAG, DEFAULT_PROVIDER as DEFAULT_PROVIDER_FLAG, EMBED_MODE, MAX_REQUESTS_PER_IP_ENV, MAX_OUTPUT_TOKENS } from "@/lib/flags";
+import { EMBED_MODE, MAX_REQUESTS_PER_IP_ENV, MAX_OUTPUT_TOKENS } from "@/lib/flags";
 import {
   DIVIDER,
   FOLLOW_UP_SYSTEM_PROMPT,
@@ -30,7 +30,7 @@ export async function POST(request: NextRequest) {
 
   const body = await request.json();
   const { prompt, redesignMarkdown, previousPrompts, pages } = body;
-  let { provider, model } = body;
+  const { provider, model } = body;
 
   // In embed mode, we previously locked provider/model to defaults.
   // Now we allow selection from the client; caps and rate limits still apply.
@@ -224,7 +224,7 @@ export async function PUT(request: NextRequest) {
 
   const body = await request.json();
   const { prompt, previousPrompts, selectedElementHtml, pages, files } = body;
-  let { provider, model } = body;
+  const { provider, model } = body;
 
   // Allow provider/model selection in embed mode; keep demo safeguards elsewhere.