Add landing page, referral system, usage quotas, search API management, and yearly pricing

- Separate workspace landing from login for better UX
- Referral system rewards both parties with Pro days
- Quota enforcement prevents abuse without breaking endpoints
- 7-day free trial with auto-downgrade on expiry
- Admin-managed search provider config (SearXNG, Bing)
- 15% discount on annual subscriptions
- MCP search server wrapping opencode search
- Fix discovery module field name mismatch causing 422

backend/app/services/search.py

@@ -0,0 +1,102 @@
+import logging
+from typing import List, Dict, Optional
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from app.models.search_provider import SearchProvider
+
+logger = logging.getLogger(__name__)
+
+IGNORE_DOMAINS = [
+    "google.com", "facebook.com", "twitter.com", "instagram.com",
+    "youtube.com", "reddit.com", "amazon.com", "ebay.com",
+    "wikipedia.org", "linkedin.com", "pinterest.com", "baidu.com",
+    "bing.com",
+]
+
+
+class SearchService:
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def search(self, query: str, limit: int = 10) -> List[Dict[str, str]]:
+        providers = await self._get_enabled_providers()
+        for provider in providers:
+            try:
+                return await self._search_provider(provider, query, limit)
+            except Exception as e:
+                logger.warning(f"Search provider {provider.provider_type} failed: {e}")
+        return []
+
+    async def _get_enabled_providers(self) -> List[SearchProvider]:
+        result = await self.db.execute(
+            select(SearchProvider)
+            .where(SearchProvider.enabled == True)
+            .order_by(SearchProvider.priority)
+        )
+        return list(result.scalars().all())
+
+    async def _search_provider(self, provider: SearchProvider, query: str, limit: int) -> List[Dict[str, str]]:
+        pt = provider.provider_type
+        if pt == "searxng":
+            return await searxng_search(provider.api_endpoint, query, limit)
+        elif pt == "bing":
+            return await bing_search(provider.api_key, query, limit)
+        else:
+            raise ValueError(f"Unknown provider type: {pt}")
+
+
+async def searxng_search(endpoint: Optional[str], query: str, limit: int) -> List[Dict[str, str]]:
+    if not endpoint:
+        raise ValueError("SearXNG endpoint not configured")
+    import httpx
+    async with httpx.AsyncClient(timeout=15.0) as client:
+        resp = await client.get(
+            endpoint.rstrip("/") + "/search",
+            params={"q": query, "format": "json", "language": "zh-CN,en", "categories": "general"},
+            headers={"User-Agent": "TradeMate/1.0"},
+        )
+        if resp.status_code != 200:
+            raise ValueError(f"SearXNG returned {resp.status_code}")
+        data = resp.json()
+        results = []
+        for item in (data.get("results", []) if isinstance(data, dict) else data):
+            url = item.get("url", "")
+            if any(d in url for d in IGNORE_DOMAINS):
+                continue
+            results.append({
+                "title": (item.get("title") or url)[:100],
+                "url": url.rstrip("/"),
+                "snippet": (item.get("content") or item.get("snippet") or "")[:200],
+            })
+            if len(results) >= limit:
+                break
+        return results
+
+
+async def bing_search(api_key: Optional[str], query: str, limit: int) -> List[Dict[str, str]]:
+    if not api_key:
+        raise ValueError("Bing API key not configured")
+    import httpx
+    async with httpx.AsyncClient(timeout=15.0) as client:
+        resp = await client.get(
+            "https://api.bing.microsoft.com/v7.0/search",
+            params={"q": query, "count": min(limit, 50), "mkt": "en-US", "textFormat": "Raw"},
+            headers={"Ocp-Apim-Subscription-Key": api_key},
+        )
+        if resp.status_code != 200:
+            raise ValueError(f"Bing returned {resp.status_code}")
+        data = resp.json()
+        results = []
+        for item in data.get("webPages", {}).get("value", []):
+            url = item.get("url", "")
+            if any(d in url for d in IGNORE_DOMAINS):
+                continue
+            results.append({
+                "title": (item.get("name") or url)[:100],
+                "url": url.rstrip("/"),
+                "snippet": (item.get("snippet") or "")[:200],
+            })
+            if len(results) >= limit:
+                break
+        return results
+