Rename all arch references to plano across the codebase

Complete rebrand from "Arch"/"archgw" to "Plano" including:
- Config files: arch_config_schema.yaml, workflow, demo configs
- Environment variables: ARCH_CONFIG_* → PLANO_CONFIG_*
- Python CLI: variables, functions, file paths, docker mounts
- Rust crates: config paths, log messages, metadata keys
- Docker/build: Dockerfile, supervisord, .dockerignore, .gitignore
- Docker Compose: volume mounts and env vars across all demos/tests
- GitHub workflows: job/step names
- Shell scripts: log messages
- Demos: Python code, READMEs, VS Code configs, Grafana dashboard
- Docs: RST includes, code comments, config references
- Package metadata: package.json, pyproject.toml, uv.lock

External URLs (docs.archgw.com, github.com/katanemo/archgw) left as-is.

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

demos/shared/chatbot_ui/.vscode/launch.json

@@ -15,7 +15,7 @@
         "LLM": "1",
         "CHAT_COMPLETION_ENDPOINT": "http://localhost:10000/v1",
         "STREAMING": "True",
-        "ARCH_CONFIG": "../../samples_python/weather_forecast/arch_config.yaml"
+        "PLANO_CONFIG": "../../samples_python/weather_forecast/plano_config.yaml"
       }
     },
     {
@@ -29,7 +29,7 @@
         "LLM": "1",
         "CHAT_COMPLETION_ENDPOINT": "http://localhost:12000/v1",
         "STREAMING": "True",
-        "ARCH_CONFIG": "../../samples_python/weather_forecast/arch_config.yaml"
+        "PLANO_CONFIG": "../../samples_python/weather_forecast/plano_config.yaml"
       }
     },
   ]

demos/shared/chatbot_ui/common.py

@@ -37,7 +37,7 @@ def chat(
 
     try:
         response = client.chat.completions.create(
-            # we select model from arch_config file
+            # we select model from plano_config file
             model="None",
             messages=history,
             temperature=1.0,
@@ -86,7 +86,7 @@ def create_gradio_app(demo_description, client):
 
             with gr.Column(scale=2):
                 chatbot = gr.Chatbot(
-                    label="Arch Chatbot",
+                    label="Plano Chatbot",
                     elem_classes="chatbot",
                 )
                 textbox = gr.Textbox(
@@ -110,7 +110,7 @@ def process_stream_chunk(chunk, history):
     delta = chunk.choices[0].delta
     if delta.role and delta.role != history[-1]["role"]:
         # create new history item if role changes
-        # this is likely due to arch tool call and api response
+        # this is likely due to Plano tool call and api response
         history.append({"role": delta.role})
 
     history[-1]["model"] = chunk.model
@@ -159,7 +159,7 @@ def convert_prompt_target_to_openai_format(target):
 
 def get_prompt_targets():
     try:
-        with open(os.getenv("ARCH_CONFIG", "config.yaml"), "r") as file:
+        with open(os.getenv("PLANO_CONFIG", "config.yaml"), "r") as file:
             config = yaml.safe_load(file)
 
             available_tools = []
@@ -181,7 +181,7 @@ def get_prompt_targets():
 
 def get_llm_models():
     try:
-        with open(os.getenv("ARCH_CONFIG", "config.yaml"), "r") as file:
+        with open(os.getenv("PLANO_CONFIG", "config.yaml"), "r") as file:
             config = yaml.safe_load(file)
 
             available_models = [""]

demos/shared/grafana/dashboards/envoy_overview.json

@@ -787,7 +787,7 @@
   },
   "timepicker": {},
   "timezone": "browser",
-  "title": "Arch Gateway Dashboard",
+  "title": "Plano Gateway Dashboard",
   "uid": "adt6uhx5lk8aob",
   "version": 1,
   "weekStart": ""

demos/shared/test_runner/common.py

@@ -30,6 +30,6 @@ def get_arch_messages(response_json):
         arch_messages_str = arch_state.get("messages", "[]")
         # parse messages into json object
         arch_messages = json.loads(arch_messages_str)
-        # append messages from arch gateway to history
+        # append messages from Plano gateway to history
         return arch_messages
     return []