feat: add VS Code policy tooling

[jamilahmadzai]

Closes #10

Summary

• Adds tools/vscode-extension, a TypeScript VS Code extension for APort policy development.
• Provides an aport-policy language contribution with syntax highlighting, snippets, and language configuration.
• Adds JSON schema validation for APort policy packs.
• Adds validation and sample-policy commands.
• Implements completion suggestions for common policy fields.
• Includes an example refund policy, documentation, and unit tests for the policy parser/validator.

Testing

cd tools/vscode-extension
npm install --no-audit
npm test
npm run check
npm pack --dry-run
git diff --check

Result:

6 Node tests passed.
TypeScript compile and syntax checks passed.
Package dry-run completed.

Payout

Payment method: PayPal jamilurrehman722@gmail.com.