fix(nodejs): narrow required route parameters

[ShuoRen-TT]

Summary

• derive a typed IdParamContext from the existing IdParamSchema
• read route IDs through c.req.valid("param") in checkout, order, and simulation handlers
• remove all 12 string | undefined TypeScript errors without non-null assertions or duplicate validation
• add focused tests for present and missing route IDs

Root cause

The route handlers were declared with a generic Hono Context, so c.req.param("id") was typed as string | undefined. Although every affected route already uses zValidator("param", IdParamSchema, ...), that validated input type did not flow into the separately declared class handlers.

This change makes the handler context carry the Zod-derived parameter input/output type and consumes the value from Hono's validated request data.

Validation

• changed-file strict TypeScript check: passed
• focused route-ID tests: passed, 2/2
• Hono runtime smoke test: GET /items/item-123 returned 200 with {"id":"item-123"}
• Prettier, codespell, whitespace, and private-key checks: passed
• this branch removes all 12 route-parameter errors; the only remaining standalone npm run build errors are the 8 discovery-profile errors fixed by fix(nodejs): align discovery profile registries #123
• combined verification with fix(nodejs): align discovery profile registries #123:
  • npm run build: passed
  • npm test: passed, 3/3 tests

Related work

This PR is independently mergeable and fixes all route-parameter typing
errors. The current main branch still has separate discovery-profile type
errors tracked by #114 and fixed by #123. With both changes present,
npm run build and npm test pass.

Closes #124