Update stale API endpoints and model chains

- Instagram: migrate /v1/ to /v2/ ScrapeCreators endpoint (v1 deprecated Feb 2026)
- OpenAI: switch fallback chain to [gpt-5-mini, gpt-4.1-mini, gpt-4.1] (8x cheaper,
  gpt-5-mini is the first mini model supporting web_search with filters.allowed_domains)
- xAI: use explicit grok-4-1-fast-non-reasoning (bare name aliases to reasoning variant)
- xAI: pass from_date/to_date natively to x_search tool config instead of prompt-only
- Polymarket: correct rate limit comment (15K/10s, not 350/10s)

scripts/lib/xai_x.py

@@ -91,11 +91,11 @@ def search_x(
     # Adjust timeout based on depth (generous for API response time)
     timeout = 90 if depth == "quick" else 120 if depth == "default" else 180
 
-    # Use Agent Tools API with x_search tool
+    # Use Agent Tools API with x_search tool (native date filtering)
     payload = {
         "model": model,
         "tools": [
-            {"type": "x_search"}
+            {"type": "x_search", "from_date": from_date, "to_date": to_date}
         ],
         "input": [
             {