[Devcontainers] Optimize hostRequirements memory threshold for cross-machine compatibility

### Is your feature request related to a problem?
The current `.devcontainer/devcontainer.json` file enforces a strict `hostRequirements` memory requirement of `9gb`. While suitable for high-end systems, this rigid threshold can cause unnecessary friction, startup blocks, or local performance constraints for developers working on mid-range host machines or resource-restricted CI/CD testing environments.

### Describe the solution you'd like
Lower or optimize the host memory requirement in `devcontainer.json` (e.g., to `4gb` or making it more flexible) to improve cross-machine compatibility and developer onboarding efficiency without impacting core container stability.

### Additional context
Optimizing container resource constraints helps broaden accessibility for open-source contributors running local development instances.