feat(scripts): add Postman collection generation to project setup (#112)

setup-project.sh now generates postman/collection.json (Health, Auth,
Resources folders, base_url/auth_token variables, collection-level
pre-request script that injects the bearer token), a platform-aware
postman/environment.json (port 3000 for Node, 8787 for Workers), and a
project README with import and regeneration instructions.

generate-openapi-docs.sh now tags the starter spec endpoints and, after
exporting the spec, regenerates the Postman collection from it via
openapi-to-postmanv2, then re-applies the base_url/auth_token variables
and the auth pre-request script the converter cannot know about.

Closes #59

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: PAMulligan