nodeset/v1: allow for postgres resources override

[zytek]

Added the ability to specify resources for the Postgres component in the nodeset composite component.

1. Added PostgresResources field to Props struct - This allows users to specify CPU and memory resource requirements for the PostgreSQL component using a map[string]map[string]string structure.

2. Updated component logic - Modified the nodeSet function to include the specified resources in the PostgreSQL Helm chart values under the primary.resources path, which follows the Bitnami PostgreSQL chart structure.

3. Added comprehensive tests - Created three new test functions:

   • TestNodeSetWithPostgresResources - Verifies PostgreSQL resources are properly applied when specified
   • TestNodeSetBackwardCompatibility - Ensures existing code without specifying resources continues to work
   • TestNodeSetWithEmptyPostgresResources - Tests that empty resources map works correctly

4. Fixed linting issues - Removed unnecessary nil check for map as recommended by staticcheck

• Backward Compatible: Existing code using the component without specifying PostgresResources will continue to work
• Flexible Resource Specification: Users can specify both requests and limits for CPU and memory
• Proper Integration: Resources are passed to the underlying PostgreSQL Helm chart through the correct value path
• Well Tested: Comprehensive test coverage including edge cases and backward compatibility

nodesetProps := &nodesetv1.Props{
    Namespace: "my-namespace",
    Size: 3,
    PostgresResources: map[string]map[string]string{
        "requests": {
            "cpu":    "500m",
            "memory": "512Mi",
        },
        "limits": {
            "cpu":    "1000m",
            "memory": "1Gi",
        },
    },
    NodeProps: [...], // chainlink node configurations
}

All tests pass and the code passes linting without any issues:

• ✅ All existing tests continue to pass (backward compatibility)
• ✅ New tests verify PostgreSQL resource functionality
• ✅ Code passes golangci-lint with zero issues