Give plugin settings capability-style input metadata

[matteomekhail]

Summary

• add semantic types and path templates to PluginSetting
• preserve validation constraints and input hints in both generated manifest paths
• pass all setting metadata to the shared dynamic input renderer
• add serialization coverage, example usage, and documentation

Validation

• ./gradlew test
• ./gradlew :composeApp:jvmTest --tests org.wip.plugintoolkit.features.plugin.ui.PluginSettingsLayoutRegressionTest

Closes #3