Feat/validate lucide icons

[NeonCharlie-24]

Description

Adds Lucide icon name validation to Pydantic models. When a config file specifies an icon field, the value is now checked against the set of valid PascalCase Lucide icon names at load time. Invalid icons produce a ValidationError with a clear error message.

• _IconValidatorMixin in config.py — a Pydantic model validator applied to FeatureConfig, ExampleCategory, and PersonaItemConfig
• lucide_icons.py — reads a pre-generated JSON registry of 1,861 valid icon names
• _lucide_icon_names.json — static registry generated from the installed lucide-react package
• generate_icon_names.py — generator script that introspects the local lucide-react Node package exports to get the ground truth PascalCase names used by the front-end
• 9 tests covering the icon registry, acceptance of valid icons across all three models, rejection of invalid icons, and default icon validation

Issues

Closes #6

Other Notes

• One of the biggest trade-offs for this implementation is whether or not to regenerate the list of valid icon names on app startup. Since the list only changes if we change the lucide-react version on the front-end, it doesn't make sense to re-compute the static list every time we start the app. The name generation script will need to be run manually when we change the version, but a CI workflow can enforce that the committed icon list stays in sync with the installed package version.
• The generator script requires node_modules to be installed in phd-advisor-frontend/ (npm ci or npm install). It does not require network access beyond the npm registry.
• For persona YAML files, an invalid icon will cause the persona to be skipped at startup (with a warning log) rather than crashing the app. For top-level config icons (features, example categories), it will fail hard at startup.

Made with Cursor.

[NeonDaniel]

Looks good. In the future, we can run that script to update icon names in some GHA automation so things are always up-to-date