refactor: consolidate backend config into versions.tf across all modules

Merges the separate backend.tf terraform{} block into versions.tf so
each module has a single terraform{} block. Prevents Terraform from
writing auto-detected required_providers into backend.tf (alphabetically
first), which caused duplicate provider errors on subsequent applies.

Also skips apply prompt for modules with no planned changes, and updates
create-aws-account.sh to scaffold new accounts with the consolidated layout.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: adityataps

providers/aws/accounts/certs/tapshalkar-com-certs/backend.tf

@@ -6,6 +6,11 @@ terraform {
       version = "~> 5.0"
     }
   }
+
+  backend "gcs" {
+    # bucket is set via -backend-config or backend.hcl (gitignored)
+    prefix = "aws/accounts/certs/tapshalkar-com-certs"
+  }
 }
 
 provider "aws" {

providers/aws/accounts/certs/tapshalkar-com-certs/versions.tf

@@ -6,6 +6,11 @@ terraform {
       version = "~> 5.0"
     }
   }
+
+  backend "gcs" {
+    # bucket is set via -backend-config or backend.hcl (gitignored)
+    prefix = "aws/accounts/management"
+  }
 }
 
 provider "aws" {

providers/aws/accounts/management/tapshalkar-com/backend.tf

@@ -6,6 +6,11 @@ terraform {
       version = "~> 5.0"
     }
   }
+
+  backend "gcs" {
+    # bucket is set via -backend-config or backend.hcl (gitignored)
+    prefix = "aws/accounts/personal/tapshalkar-com-personal"
+  }
 }
 
 provider "aws" {

providers/aws/accounts/management/tapshalkar-com/versions.tf

@@ -6,6 +6,11 @@ terraform {
       version = "~> 5.0"
     }
   }
+
+  backend "gcs" {
+    # bucket is set via -backend-config or backend.hcl (gitignored)
+    prefix = "aws/accounts/personal/tapshalkar-com-sandbox"
+  }
 }
 
 provider "aws" {

providers/aws/accounts/personal/tapshalkar-com-personal/backend.tf

@@ -6,6 +6,11 @@ terraform {
       version = "~> 5.0"
     }
   }
+
+  backend "gcs" {
+    # bucket is set via -backend-config or backend.hcl (gitignored)
+    prefix = "aws/org"
+  }
 }
 
 provider "aws" {