feat: add get_weather MCP tool using wttr.in API

- New agent/weather_mcp.py: stdio MCP server with get_weather(location)
  that returns a short conversational summary (temp, conditions, high/low)
- Register weather toolset in build_mcp_toolsets() alongside web-access
- Update system prompt with Weather section

agent/agent.py

@@ -63,12 +63,17 @@ SYSTEM_PROMPT = textwrap.dedent("""\
 
     # Web access
     You have web_search and web_scrape tools. Use them when the user asks about
-    current events, recent news, prices, weather, sports scores, or anything
+    current events, recent news, prices, sports scores, or anything
     that may have changed since your training data. Search first, then scrape
     a result only if you need more detail. Answer from what you find, in your
     normal conversational style — don't cite sources formally, just mention the
     source naturally ("according to..."). If a search comes up empty, say so
     briefly and move on.
+
+    # Weather
+    You can check the weather for any location. Use get_weather when the user
+    asks about current conditions, temperature, or forecasts. It returns a
+    short summary — relay it naturally in your own words.
 """)
 
 
@@ -178,6 +183,21 @@ def build_mcp_toolsets() -> list[mcp.MCPToolset]:
         )
         logger.info("Web-access MCP toolset enabled (Firecrawl at %s)", FIRECRAWL_BASE)
 
+    python_bin = os.path.join(os.path.dirname(os.path.abspath(__file__)), ".venv", "bin", "python")
+    weather_mcp_script = os.path.join(os.path.dirname(os.path.abspath(__file__)), "weather_mcp.py")
+    toolsets.append(
+        mcp.MCPToolset(
+            id="weather",
+            mcp_server=mcp.MCPServerStdio(
+                command=python_bin,
+                args=[weather_mcp_script],
+                env={**os.environ},
+                client_session_timeout_seconds=30,
+            ),
+        )
+    )
+    logger.info("Weather MCP toolset enabled (wttr.in)")
+
     extra = os.environ.get("EXTRA_MCP_SERVERS", "")
     if extra:
         try: