fix(terraform-patterns): align plugin.json version to repo versioning (2.1.2)

Review gate flagged version 1.0.0 as non-compliant with CLAUDE.md rule:
"Version follows repo versioning." Updated to 2.1.2.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

engineering/terraform-patterns/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "terraform-patterns",
   "description": "Terraform infrastructure-as-code agent skill and plugin for module design patterns, state management strategies, provider configuration, security hardening, and CI/CD plan/apply workflows. Covers mono-repo vs multi-repo, workspaces, policy-as-code, and drift detection.",
-  "version": "1.0.0",
+  "version": "2.1.2",
   "author": {
     "name": "Alireza Rezvani",
     "url": "https://alirezarezvani.com"