feat: add secret type to env:add command

[batosai]

🔗 Linked issue

N/A

❓ Type of change

• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• [ x ] ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Adds support for the secret type to the env:add command, both through the interactive prompt and the --type=secret flag.

For example, node ace env:add API_KEY my_secret --type=secret now generates API_KEY: Env.schema.secret() in start/env.ts. The value is written to .env and omitted from .env.example.

Includes tests for both usages. All 6 command tests, TypeScript checks, and ESLint checks on the changed files pass.

Documentation PR: adonisjs/v7-docs#86

📝 Checklist

• I have linked an issue or discussion.
• [ x ] I have updated the documentation accordingly.

[RomainLanz]

Thanks!