Add getStaticPaths for dynamic SSG route generation

[JoviDeCroock]

Summary

• Replaces prerender() with getStaticPaths() on route modules — returns RouteParams[] instead of full path strings, decoupling route modules from their URL patterns
• Adds buildPathFromSegments() helper that constructs full paths from route segments + params at build time
• Adds a /products/:productId dynamic SSG example route to the basic example app
• E2E test verifies dynamic SSG routes produce static HTML files and serve correctly
• Updates all docs, example docs, and skill files to reflect the new API

Test plan

• Unit tests pass (16/16)
• E2E node-build test verifies prerendered HTML files exist for /products/1, /products/2, /products/3
• E2E node-build test verifies the server serves dynamic SSG pages with correct content

🤖 Generated with Claude Code