Add real-time query handling: pre-search enrichment + routing fix

- router.py: add _MEDIUM_FORCE_PATTERNS to block weather/news/price
  queries from light tier regardless of LLM classification
- agent.py: add _REALTIME_RE and _searxng_search_async(); real-time
  queries now run SearXNG search concurrently with URL fetch + memory
  retrieval, injecting snippets into medium system prompt
- tests/use_cases/weather_now.md: use case test for weather queries

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

router.py

@@ -23,6 +23,16 @@ _LIGHT_PATTERNS = re.compile(
     re.IGNORECASE,
 )
 
+# Queries that require live data — never answer from static knowledge
+_MEDIUM_FORCE_PATTERNS = re.compile(
+    r"\b(weather|forecast|temperature|rain(ing)?|snow(ing)?|humidity|wind speed"
+    r"|today.?s news|breaking news|latest news|news today|current events"
+    r"|bitcoin price|crypto price|stock price|exchange rate|usd|eur|btc"
+    r"|right now|currently|at the moment|live score|score now|score today"
+    r"|open now|hours today|is .+ open)\b",
+    re.IGNORECASE,
+)
+
 # ── LLM classification prompt ─────────────────────────────────────────────────
 CLASSIFY_PROMPT = """Classify the message. Output ONLY one word: light, medium, or complex.
 
@@ -90,7 +100,12 @@ class Router:
         if force_complex:
             return "complex", None
 
-        # Step 0: regex pre-classification for obvious light patterns
+        # Step 0a: force medium for real-time / live-data queries
+        if _MEDIUM_FORCE_PATTERNS.search(message.strip()):
+            print(f"[router] regex→medium (real-time query)", flush=True)
+            return "medium", None
+
+        # Step 0b: regex pre-classification for obvious light patterns
         if _LIGHT_PATTERNS.match(message.strip()):
             print(f"[router] regex→light", flush=True)
             return await self._generate_light_reply(message, history)