INFRA-2970: fix: show diff in terraform fmt CI check

[scrubious]

Summary

• Add -diff flag to terraform fmt -check -recursive in the analysis workflow

Previously a fmt failure only printed the affected file names plus exit code 3, giving no indication of what was wrong without running terraform fmt locally. With -diff, CI prints the full unified diff for every unformatted block — same signal you'd get from git diff after running fmt.

Before

Run terraform fmt -check -recursive
examples/nodejs-demo-int/main.tf
modules/data-plane/elasticache-serverless/main.tf
Error: Terraform exited with code 3.

After

Run terraform fmt -check -diff -recursive
--- old/modules/data-plane/elasticache-serverless/main.tf
+++ new/modules/data-plane/elasticache-serverless/main.tf
@@ -51,7 +51,6 @@
   lifecycle {
     precondition {
-      condition     = ...
+      condition = ...
     }
   }