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

[PAMulligan]

Summary

Implements #59 -- new projects ship with a ready-to-import Postman collection, and the docs script keeps the collection in sync with the OpenAPI spec.

setup-project.sh

Generates three new artifacts in every project (both platforms, dry-run aware):

• postman/collection.json -- Postman Collection v2.1 with the required structure:
  • Health folder: GET {{base_url}}/health (with a status-200 test) and GET {{base_url}}/ -- both work immediately against the starter app
  • Auth folder: POST {{base_url}}/auth/login placeholder whose test script captures token from a successful login into the auth_token environment variable
  • Resources folder: empty, documented as the landing spot for generated CRUD endpoints
  • Collection-level pre-request script that injects Authorization: Bearer {{auth_token}} on every request once the token is set
  • Collection variables base_url / auth_token as fallbacks when no environment is selected
• postman/environment.json -- local environment with base_url (platform-aware: http://localhost:3000 for Node, http://localhost:8787 for Workers) and auth_token (type secret so Postman masks it)
• README.md -- project README with quickstart plus Postman import steps and the regeneration command

generate-openapi-docs.sh

• Tags the starter spec endpoints with Health so folder-by-tags conversion mirrors the starter collection layout
• After writing the spec, regenerates postman/collection.json from it via openapi-to-postmanv2 (folderStrategy=Tags), then post-processes the output: renames the converter'''s {{baseUrl}} to Nerva'''s {{base_url}}, restores the base_url/auth_token variables, and re-applies the auth pre-request script the converter cannot know about
• Conversion failure degrades to a warning -- the spec generation flow is unaffected

Verification

• bash -n and ShellCheck v0.11.0 (--severity=warning, matching CI) clean on both scripts
• Full e2e run of setup-project.sh (Node platform): both JSON files parse, folder/variable/script structure asserted with node, README fences and platform substitutions render correctly
• Full e2e run of generate-openapi-docs.sh inside the generated project: OpenAPI 3.1 spec converts successfully, {{baseUrl}} fully normalized, Health folder produced from tags, auth injection present in the regenerated collection
• Cloudflare variant verified via --dry-run flow

Closes #59

🤖 Generated with Claude Code