chore: upgrade BMAD framework to skill-based architecture

Migrates from slash-command files (.claude/commands, .cursor/commands)
to the new skill-based architecture with workflow step files.

_bmad/tea/workflows/testarch/bmad-testarch-ci/workflow-plan.md

@@ -0,0 +1,20 @@
+    # Workflow Plan: testarch-ci
+
+    ## Create Mode (steps-c)
+    - step-01-preflight.md
+
+- step-02-generate-pipeline.md
+- step-03-configure-quality-gates.md
+- step-04-validate-and-summary.md
+
+  ## Validate Mode (steps-v)
+  - step-01-validate.md
+
+  ## Edit Mode (steps-e)
+  - step-01-assess.md
+  - step-02-apply-edit.md
+
+  ## Outputs
+  - CI config (e.g., {project-root}/.github/workflows/test.yml)
+
+- Pipeline guidance and artifacts configuration