feat(1080): add bundled postgresql resources to helm chart

[Sim-sat]

Description

What problem does this PR solve?
The helm documentation said it would start the database but didn't contain any charts for it.

How did you implement the solution?
I added a template for postgres. I also adjusted the default values to allow private networks because most people will use a port forward to quickly test the app. It should work with a single command to make it as easy as possible to test.

Linked Issue: Closes #1080

How to Test

I tested it using Kind (Kubernetes in docker) and everything is starting fine and sign up is working.

PR Type

• Issue (bug fix)
• New Feature
• Refactor
• Documentation

Checklist

All PRs:

• [MANDATORY - ALL] Integrity & License: I certify this is my own work, free of malicious code, and I agree to the License terms.

New features only:

• [MANDATORY for new feature] Alignment: I have raised a GitHub issue and it was reviewed/approved by maintainers or it was approved on Discord.

Frontend changes (SparkyFitnessFrontend/ or src/):

• [MANDATORY for Frontend changes] Quality: I have run pnpm run validate and it passes.
• [MANDATORY for Frontend changes] Translations: I have only updated the English (en) translation file.

Backend changes (SparkyFitnessServer/):

• [MANDATORY for Backend changes] Code Quality: I have run typecheck, lint, and tests. New files use TypeScript, new endpoints have Zod schemas, and new endpoints include tests.
• [MANDATORY for Backend changes] Database Security: I have updated rls_policies.sql for any new user-specific tables.

UI changes (components, screens, pages):

• [MANDATORY for UI changes] Screenshots: I have attached Before/After screenshots below.

[gemini-code-assist]

Code Review

This pull request introduces a bundled PostgreSQL instance to the Helm chart, including a StatefulSet, Service, and Secret management. It also adds port-forwarding instructions to the NOTES.txt, a connection test, and updates the default CORS configuration for local development. Feedback includes correcting the PostgreSQL image tag to a valid version (e.g., 17-alpine), reverting the default CORS policy for private networks to maintain a secure baseline, and sourcing the database name from the Kubernetes secret in the StatefulSet to ensure consistency when using custom secrets.