chore: Update .gitignore with terraform, helm, and session file patterns

- Add terraform patterns (.terraform/, *.tfstate, *.tfstate.backup, tfplan, *.tfplan)
- Add helm charts directory (deployment/helm/*/charts/)
- Add session file patterns (*_HANDOFF.md, *_IMPLEMENTATION_PLAN.md)

This prevents committing generated artifacts and temporary working documents.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: manavgup

.gitignore

@@ -120,3 +120,17 @@ uv.lock
 archive/
 .secrets
 .vars
+
+# Terraform
+.terraform/
+*.tfstate
+*.tfstate.backup
+tfplan
+*.tfplan
+
+# Helm
+deployment/helm/*/charts/
+
+# Session/temporary documentation
+*_HANDOFF.md
+*_IMPLEMENTATION_PLAN.md