fix: complete web search integration with query enrichment

Fixes several issues with the web search migration to Librarian:

- Update Steward routing guidelines for web search/weather → Librarian
- Register search_web, read_url, read_urls_batch tools with Librarian agent
- Update Librarian system prompt with web search documentation
- Fix query enrichment not being passed to delegations (location context)
- Add URL reading keywords to RESEARCH action type detection

Weather queries now automatically include user's stored location from
the Biographer, enabling location-aware search results.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/agents/delegation.py

@@ -100,10 +100,13 @@ def _detect_action_type(expert: str, task: str) -> ActionType:
     task_lower = task.lower()
 
     if expert == "librarian":
+        # Web search, URL reading = RESEARCH (fresh external data)
         if any(w in task_lower for w in ["search", "find", "look up", "research"]):
             if any(w in task_lower for w in ["web", "online", "internet"]):
                 return ActionType.RESEARCH
             return ActionType.RETRIEVE
+        if any(w in task_lower for w in ["read", "fetch", "url", "http"]):
+            return ActionType.RESEARCH  # Reading URLs is research
         if any(w in task_lower for w in ["create", "write", "add", "make", "new"]):
             return ActionType.CREATE
         return ActionType.RETRIEVE