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/samples_python/weather_forecast/README.md

@@ -1,11 +1,11 @@
 # Function calling
 
-This demo shows how you can use Arch's core function calling capabilities.
+This demo shows how you can use Plano's core function calling capabilities.
 
 # Starting the demo
 
 1. Please make sure the [pre-requisites](https://github.com/katanemo/arch/?tab=readme-ov-file#prerequisites) are installed correctly
-2. Start Arch
+2. Start Plano
 
 3. ```sh
    sh run_demo.sh
@@ -15,14 +15,14 @@ This demo shows how you can use Arch's core function calling capabilities.
 
 # Observability
 
-Arch gateway publishes stats endpoint at http://localhost:19901/stats. In this demo we are using prometheus to pull stats from arch and we are using grafana to visalize the stats in dashboard. To see grafana dashboard follow instructions below,
+Plano gateway publishes stats endpoint at http://localhost:19901/stats. In this demo we are using prometheus to pull stats from Plano and we are using grafana to visalize the stats in dashboard. To see grafana dashboard follow instructions below,
 
 1. Start grafana and prometheus using following command
    ```yaml
    docker compose --profile monitoring up
    ```
 2. Navigate to http://localhost:3000/ to open grafana UI (use admin/grafana as credentials)
-3. From grafana left nav click on dashboards and select "Intelligent Gateway Overview" to view arch gateway stats
+3. From grafana left nav click on dashboards and select "Intelligent Gateway Overview" to view Plano gateway stats
 
 Here is a sample interaction,
 <img width="575" alt="image" src="https://github.com/user-attachments/assets/e0929490-3eb2-4130-ae87-a732aea4d059">

demos/samples_python/weather_forecast/docker-compose-honeycomb.yaml

@@ -20,7 +20,7 @@ services:
     extra_hosts:
       - "host.docker.internal:host-gateway"
     volumes:
-      - ./config.yaml:/app/arch_config.yaml
+      - ./config.yaml:/app/plano_config.yaml
 
   otel-collector:
     build:

demos/samples_python/weather_forecast/docker-compose-jaeger.yaml

@@ -20,7 +20,7 @@ services:
     extra_hosts:
       - "host.docker.internal:host-gateway"
     volumes:
-      - ./config.yaml:/app/arch_config.yaml
+      - ./config.yaml:/app/plano_config.yaml
 
   jaeger:
     build:

demos/samples_python/weather_forecast/docker-compose-logfire.yaml

@@ -20,7 +20,7 @@ services:
     extra_hosts:
       - "host.docker.internal:host-gateway"
     volumes:
-      - ./config.yaml:/app/arch_config.yaml
+      - ./config.yaml:/app/plano_config.yaml
 
   otel-collector:
     build:

demos/samples_python/weather_forecast/docker-compose-signoz.yaml

@@ -23,7 +23,7 @@ services:
     extra_hosts:
       - "host.docker.internal:host-gateway"
     volumes:
-      - ./config.yaml:/app/arch_config.yaml
+      - ./config.yaml:/app/plano_config.yaml
 
   prometheus:
     build:

demos/samples_python/weather_forecast/docker-compose.yaml

@@ -20,4 +20,4 @@ services:
     extra_hosts:
       - "host.docker.internal:host-gateway"
     volumes:
-      - ./config.yaml:/app/arch_config.yaml
+      - ./config.yaml:/app/plano_config.yaml

demos/samples_python/weather_forecast/run_demo.sh

@@ -72,8 +72,8 @@ start_demo() {
     exit 1
   fi
 
-  # Step 4: Start Arch
-  echo "Starting Arch with config.yaml..."
+  # Step 4: Start Plano
+  echo "Starting Plano with config.yaml..."
   planoai up config.yaml
 
   # Step 5: Start Network Agent with the chosen Docker Compose file
@@ -91,8 +91,8 @@ stop_demo() {
     docker compose -f "$compose_file" down
   done
 
-  # Stop Arch
-  echo "Stopping Arch..."
+  # Stop Plano
+  echo "Stopping Plano..."
   planoai down
 }