Avanan Legacy Mcp

Please install the `avanan-legacy-mcp` MCP server into my current AI client (that's you).

Required prerequisites (do these first if not already done):
- **Install dependencies** — Install the project dependencies before building and running the server. Run: `npm install`
- **Build the server** — Build the server before starting it. Run: `npm run build`
- **Obtain Avanan API credentials** — Get the Avanan MSP SmartAPI credentials from Avanan Support and the auth handshake: application ID, token, and shared secret.

Canonical MCP server config (stdio transport):
- command: `npm`
- args: ["start"]
- required environment variables:
  - `AVANAN_APP_ID`: Application ID provided by Avanan Support (`x-av-app-id`). (example: `<your-avanan-app-id>`)
  - `AVANAN_TOKEN`: Token from the Avanan auth handshake (`x-av-token`). (example: `<your-avanan-token>`)
  - `AVANAN_SECRET`: Shared secret used to compute the `x-av-sig` HMAC. (example: `<your-avanan-secret>`)
- optional environment variables:
  - `AVANAN_REGION`: Region for the Avanan MSP SmartAPI. Valid values: `us`, `eu`, `ca`, `ap`. Defaults to JWT region claim, then `us`. (example: `<us|eu|ca|ap>`)
  - `MCP_TRANSPORT`: Transport mode. `stdio` is the default; `http` is also supported. (example: `stdio`)
  - `MCP_HTTP_PORT`: HTTP transport port when using HTTP mode. Default is 8080. (example: `<your-http-port>`)
  - `LOG_LEVEL`: Logging level. Valid values: `debug`, `info`, `warn`, `error`. Default is `info`. (example: `<debug|info|warn|error>`)

Note: README only provides local build/run instructions (`npm install`, `npm run build`, `npm start`) and does not provide a packaged portable install path. Default transport is stdio. The server also supports HTTP when `MCP_TRANSPORT=http`, but no standalone HTTP URL is configured in advance because it is launched locally. In gateway mode, Avanan credentials may be supplied per request via headers instead of environment variables: `X-Avanan-App-Id`, `X-Avanan-Token`, `X-Avanan-Secret`, and optionally `X-Avanan-Region`. The README warns that the `x-av-sig` signing algorithm is a best-guess HMAC-SHA256 implementation and should be replaced with the exact algorithm before production use.

Add this MCP server to my current client's config in the correct format for you. If you need secrets or credentials I haven't provided, ASK me — do not invent values or leave raw placeholders. After adding it, tell me how to verify the server is connected.