### Check for existing issues

- [X] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

The MCP server edit component computes `initialEnvJson` from `mcpServer.env` but never places it into the form's `initialValues.env_json`. When a user opens the edit modal for a stdio MCP server and saves without re-entering environment variables, the stdio code path parses an undefined `env_json` as `{}` and the resulting update payload overwrites the server's stored `env` with an empty object.

**Observed:** `initialValues` for the edit form does not include `env_json`, even though the component computes `initialEnvJson` from `mcpServer.env`. The stdio save path destructures `env_json` from form values, treats `undefined` as "no env supplied", and produces `parsedEnv = {}`. The update payload includes `env: {}`, and the backend persists it, deleting every stored environment variable on the server.

**Expected:** Saving a stdio MCP server without changing the environment-variable section should leave the stored `env` untouched.

**Why this matters:** Stdio MCP servers commonly depend on environment variables for upstream credentials, region se…