[Feature] Add PWD to default excluded environment keys (non-breaking)

[Chrilleweb]

Describe the feature

Add PWD to DEFAULT_EXCLUDE_KEYS so it does not trigger missing or unused warnings when referenced in code.

Proposed solution

Add PWD to the DEFAULT_EXCLUDE_KEYS list
src/core/filterIgnoredKeys.ts

fx:
export const DEFAULT_EXCLUDE_KEYS = [
'PWD',
'NODE_ENV',
'VITE_MODE',
'MODE',
'BASE_URL',
'PROD',
'DEV',
'SSR',
];

Additional context

This aligns with other default excludes such as NODE_ENV and improves signal-to-noise ratio when scanning Node.js-based projects.