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>

cli/planoai/docker_cli.py

@@ -41,7 +41,7 @@ def docker_remove_container(container: str) -> str:
 
 
 def docker_start_plano_detached(
-    arch_config_file: str,
+    plano_config_file: str,
     env: dict,
     gateway_ports: list[int],
 ) -> str:
@@ -58,7 +58,7 @@ def docker_start_plano_detached(
     port_mappings_args = [item for port in port_mappings for item in ("-p", port)]
 
     volume_mappings = [
-        f"{arch_config_file}:/app/arch_config.yaml:ro",
+        f"{plano_config_file}:/app/plano_config.yaml:ro",
     ]
     volume_mappings_args = [
         item for volume in volume_mappings for item in ("-v", volume)
@@ -115,7 +115,7 @@ def stream_gateway_logs(follow, service="plano"):
         log.info(f"Failed to stream logs: {str(e)}")
 
 
-def docker_validate_plano_schema(arch_config_file):
+def docker_validate_plano_schema(plano_config_file):
     import os
 
     env = os.environ.copy()
@@ -129,7 +129,7 @@ def docker_validate_plano_schema(arch_config_file):
             "--rm",
             *env_args,
             "-v",
-            f"{arch_config_file}:/app/arch_config.yaml:ro",
+            f"{plano_config_file}:/app/plano_config.yaml:ro",
             "--entrypoint",
             "python",
             PLANO_DOCKER_IMAGE,