Improve Awesome JEV discovery with scenarios and an Agent Skill

[erickkkyt]

Readers can now start with a task and find specific implementations to study, while the existing 10 project types remain the full-catalogue navigation.

• Add six scenario guides in English, Chinese and Japanese, with project references joined to the existing catalogue.
• Reorder all three READMEs around compact scenario discovery, the preserved 10-card featured gallery, agent search, and the full 183-project catalogue.
• Add an installable Awesome JEV discovery Skill with current public catalogue sources and evidence-aware recommendations; no API key is needed for discovery.
• Document contribution and generation workflows, keeping the catalogue as the project source of truth.

Validation: all seven tests pass (scenario integrity, local links/anchors, repeatable generation, catalogue completeness); Skill schema validation and staged credential-pattern scan pass; README Refiner static check reports zero errors or warnings. Original featured galleries match the base version exactly in all three languages. No dependencies or deployment workflows changed. Browser rendering was not independently verified.