Add Railway deployment docs to postgres README

[pranaygp]

Summary

• add a Railway deployment section to the postgres example README
• include the Deploy on Railway button for the published template
• document the curl smoke test and observability follow-up step

Testing

• not run (README-only change)

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Project	Deployment	Actions	Updated (UTC)
birthday-card-generator	Ready	Preview, Comment	Apr 12, 2026 2:57am

[Copilot]

Pull request overview

Adds Railway deployment guidance to the Postgres example README so users can deploy the template, run a quick smoke test, and verify execution via the observability deployment.

Changes:

• Replaces the “Coming soon” placeholder with a “Deploy on Railway” section.
• Adds a Deploy on Railway button/link for the published template.
• Documents a curl smoke test and a follow-up step to confirm the run in observability.

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[Copilot]

### Deploy on Railway is at the same heading level as ### Production Deployment, which makes the hierarchy confusing (it reads as a sibling section rather than a subsection). Consider making Deploy on Railway a level deeper (e.g., ####) so it clearly nests under Production Deployment.

Suggested change

	### Deploy on Railway
	#### Deploy on Railway

[VaguelySerious]

Should there be a section about security (for both the routes + the observability?) + how to point CLI to the railway deployment