feat: add news source adapters and AI article analysis

- Implement adapters for NewsAPI, GNews, NewsData, Serper Web Search,
  and Brave Search.
- Add unified fetchNews aggregator with URL deduplication.
- Wire OpenAI-compatible Kimi client for bias classification, ranking,
  summarization, and topic extraction.
- Add AI analysis prompts, response parsing, and fallback logic.
- Build ranker combining AI score, source credibility, and recency.
- Create admin Discover page and API for manual news discovery.

src/lib/news/sources/websearch.ts

@@ -0,0 +1,42 @@
+import { FetchNewsOptions, RawArticle } from '../types';
+import { getActiveKey } from '@/lib/api-keys';
+
+export async function fetchWebSearch(options: FetchNewsOptions): Promise<RawArticle[]> {
+  const apiKey = await getActiveKey('WEBSEARCH');
+  if (!apiKey) {
+    console.warn('Web search key not configured');
+    return [];
+  }
+
+  const res = await fetch('https://google.serper.dev/search', {
+    method: 'POST',
+    headers: {
+      'X-API-KEY': apiKey,
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify({
+      q: options.query,
+      num: Math.min(options.maxResults || 10, 20),
+      tbs: options.from ? `cdr:1,cd_min:${options.from.toISOString().split('T')[0]}` : undefined,
+    }),
+  });
+
+  if (!res.ok) {
+    const text = await res.text();
+    throw new Error(`Web search error ${res.status}: ${text}`);
+  }
+
+  const data = await res.json();
+
+  return (data.news || data.organic || []).map((item: Record<string, unknown>) => ({
+    title: String(item.title || ''),
+    url: String(item.link || item.url || ''),
+    sourceName: String(item.source || 'Web Search'),
+    sourceApiCode: 'websearch',
+    publishedAt: item.date ? new Date(String(item.date)) : undefined,
+    description: item.snippet ? String(item.snippet) : undefined,
+    content: undefined,
+    imageUrl: item.imageUrl ? String(item.imageUrl) : undefined,
+    raw: item,
+  }));
+}