Rename all arch references to plano (#745)

* 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>

* Update remaining arch references in docs

- Rename RST cross-reference labels: arch_access_logging, arch_overview_tracing, arch_overview_threading → plano_*
- Update label references in request_lifecycle.rst
- Rename arch_config_state_storage_example.yaml → plano_config_state_storage_example.yaml
- Update config YAML comments: "Arch creates/uses" → "Plano creates/uses"
- Update "the Arch gateway" → "the Plano gateway" in configuration_reference.rst
- Update arch_config_schema.yaml reference in provider_models.py
- Rename arch_agent_router → plano_agent_router in config example

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

* Fix remaining arch references found in second pass

- config/docker-compose.dev.yaml: ARCH_CONFIG_FILE → PLANO_CONFIG_FILE,
  arch_config.yaml → plano_config.yaml, archgw_logs → plano_logs
- config/test_passthrough.yaml: container mount path
- tests/e2e/docker-compose.yaml: source file path (was still arch_config.yaml)
- cli/planoai/core.py: comment and log message
- crates/brightstaff/src/tracing/constants.rs: doc comment
- tests/{e2e,archgw}/common.py: get_arch_messages → get_plano_messages,
  arch_state/arch_messages variables renamed
- tests/{e2e,archgw}/test_prompt_gateway.py: updated imports and usages
- demos/shared/test_runner/{common,test_demos}.py: same renames
- tests/e2e/test_model_alias_routing.py: docstring
- .dockerignore: archgw_modelserver → plano_modelserver
- demos/use_cases/claude_code_router/pretty_model_resolution.sh: container name

Note: x-arch-* HTTP header values and Rust constant names intentionally
preserved for backwards compatibility with existing deployments.

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

demos/use_cases/model_alias_routing/README.md

@@ -1,6 +1,6 @@
 # Model Alias Demo Suite
 
-This directory contains demos for the model alias feature in archgw.
+This directory contains demos for the model alias feature in Plano.
 
 ## Overview
 
@@ -48,7 +48,7 @@ model_aliases:
 ```
 
 ## Prerequisites
-- Install all dependencies as described in the main Arch README ([link](https://github.com/katanemo/arch/?tab=readme-ov-file#prerequisites))
+- Install all dependencies as described in the main Plano README ([link](https://github.com/katanemo/plano/?tab=readme-ov-file#prerequisites))
 - Set your API keys in your environment:
   - `export OPENAI_API_KEY=your-openai-key`
   - `export ANTHROPIC_API_KEY=your-anthropic-key` (optional, but recommended for Anthropic tests)
@@ -60,13 +60,13 @@ model_aliases:
    sh run_demo.sh
    ```
    - This will create a `.env` file with your API keys (if not present).
-   - Starts Arch Gateway with model alias config (`arch_config_with_aliases.yaml`).
+   - Starts Plano gateway with model alias config (`arch_config_with_aliases.yaml`).
 
 2. To stop the demo:
    ```sh
    sh run_demo.sh down
    ```
-   - This will stop Arch Gateway and any related services.
+   - This will stop Plano gateway and any related services.
 
 ## Example Requests
 
@@ -145,4 +145,4 @@ curl -sS -X POST "http://localhost:12000/v1/messages" \
 ## Troubleshooting
 - Ensure your API keys are set in your environment before running the demo.
 - If you see errors about missing keys, set them and re-run the script.
-- For more details, see the main Arch documentation.
+- For more details, see the main Plano documentation.

demos/use_cases/model_alias_routing/run_demo.sh

@@ -24,11 +24,11 @@ start_demo() {
     echo ".env file created with API keys."
   fi
 
-  # Step 3: Start Arch
-  echo "Starting Arch with arch_config_with_aliases.yaml..."
+  # Step 3: Start Plano
+  echo "Starting Plano with arch_config_with_aliases.yaml..."
   planoai up arch_config_with_aliases.yaml
 
-  echo "\n\nArch started successfully."
+  echo "\n\nPlano started successfully."
   echo "Please run the following CURL command to test model alias routing. Additional instructions are in the README.md file. \n"
   echo "curl -sS -X POST \"http://localhost:12000/v1/chat/completions\" \
     -H \"Authorization: Bearer test-key\" \
@@ -46,8 +46,8 @@ start_demo() {
 
 # Function to stop the demo
 stop_demo() {
-  # Step 2: Stop Arch
-  echo "Stopping Arch..."
+  # Step 2: Stop Plano
+  echo "Stopping Plano..."
   planoai down
 }