Add .env support and configure GNS3 server connection

- Add python-dotenv to requirements
- Load .env file in app.py
- Create .env with lab.grahampaasch.com:3080 connection
- Verified connection to GNS3 server and overgrowth project

.env

@@ -0,0 +1,2 @@
+GNS3_SERVER=http://lab.grahampaasch.com:3080
+GNS3_PROJECT_NAME=overgrowth

app.py

@@ -1,4 +1,10 @@
 import gradio as gr
+import os
+from dotenv import load_dotenv
+
+# Load environment variables from .env file
+load_dotenv()
+
 from agent.pipeline import (
     analyze_change,
     oob_troubleshoot,

requirements.txt

@@ -4,3 +4,4 @@ requests
 mcp
 paramiko
 netmiko
+python-dotenv