feat: rank professionals by completed services + score, search by name/profession/city

- GET /professionals now accepts ?search= instead of ?city=/page/limit
- Filters each word across profession, user name, and user city (AND of OR)
- Counts completed services per professional via Prisma _count filter
- Sorts: most completed services first, then highest average_score
- Always returns top 7 results

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/professionals/professionals.controller.ts

@@ -15,10 +15,8 @@ export class ProfessionalsController {
 
   @Get()
   findAllActive(@Req() req) {
-    const page = +(req.query.page || 1);
-    const limit = +(req.query.limit || 20);
-    const city = req.query.city as string | undefined;
-    return this.pros.findAllActive(page, limit, city);
+    const search = req.query.search as string | undefined;
+    return this.pros.findAllActive(search);
   }
 
   @Get('pending')