Description

Fixes #10872.

Currently, commands like new and addon validate their arguments before loading the options defined in the target blueprint. This causes the CLI to warn that "The option 'x' is not registered" even if the blueprint explicitly defines that option in its availableOptions.

The Fix

1. Execution Order: Modified lib/models/command.js to execute the beforeRun hook (which calls mergeBlueprintOptions) inside validateAndRun before the argument validation/parsing occurs.
2. Blueprint Lookup: Updated lib/utilities/merge-blueprint-options.js. Since nopt parsing hasn't happened yet at this stage, the helper now manually parses rawArgs to find the blueprint name (handling -b, --blueprint, and defaulting to app/addon), ensuring the correct options are merged.
3. Regression Fix: Fixed a crash in mergeDuplicateOption that was exposed by this timing change. Previously, if a blueprint option had undefined aliases, flatMap would throw an error. Added a fallback || [] to prevent this.

Reproduction

1. Create a blueprint that has a custom option (e.g., --pizza in availableOptions).
2. Run ember new my-app --pizza=cheese.
3. Before: The CLI warns: The option '--pizza' is not registered with the 'new' command.
4. After: The CLI accepts the option silently and passes it to the blueprint as expected.

Testing

• Added a unit test in tests/unit/models/command-test.js to verify beforeRun is called before argument parsing.
• Verified manually that ember new and ember addon no longer emit warnings for valid blueprint flags.