feat(vscode): .env file into python env

[benfdking]

• Picks up the .env file specified through the Python extension and places it into the Python environment that the extension calls are made in.

[Copilot]

Pull Request Overview

This PR enhances the VS Code extension to load environment variables (including those from a .env file) into the Python environment for SQLMesh commands, and refactors test helpers for TCloud setup.

• Extract common TCloud authentication and version helpers into tcloud_utils.ts
• Introduce getPythonEnvVariables and merge its output into sqlmeshExec and sqlmeshLspExec
• Add end-to-end tests (python_env.spec.ts) to verify .env variable injection

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vscode/extension/tests/tcloud_utils.ts	New shared helpers for TCloud authentication and version setup
vscode/extension/tests/tcloud.spec.ts	Removed duplicate helpers and import from tcloud_utils.ts
vscode/extension/tests/python_env.spec.ts	New tests for verifying .env variable injection in Python env
vscode/extension/src/utilities/sqlmesh/sqlmesh.ts	Merge Python env vars into process environment for SQLMesh cmds
vscode/extension/src/utilities/common/python.ts	Add getPythonEnvVariables to fetch env vars from Python ext

Comments suppressed due to low confidence (1)

vscode/extension/tests/python_env.spec.ts:16

• [nitpick] The parameter name sushi_path uses snake_case, which is inconsistent with the project's camelCase convention. Rename it to sushiPath for consistency.

function writeEnvironmentConfig(sushi_path: string) {