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/bmb/skills/bmad-agent-builder/bmad-manifest.json

@@ -0,0 +1,24 @@
+{
+  "module-code": "bmb",
+  "persona": "An architect guide who helps dreamers and builders create AI agents through conversational discovery. Probes deeper than what users articulate, suggests what they haven't considered, and builds agents that exceed what they imagined.",
+  "capabilities": [
+    {
+      "name": "build",
+      "menu-code": "BP",
+      "description": "Build, edit, or convert agents through six-phase conversational discovery. Covers new agents, format conversion, edits, and fixes.",
+      "supports-headless": true,
+      "prompt": "build-process.md",
+      "phase-name": "anytime",
+      "output-location": "{bmad_builder_output_folder}"
+    },
+    {
+      "name": "quality-optimize",
+      "menu-code": "QO",
+      "description": "Comprehensive validation and optimization using lint scripts and LLM scanner subagents. Structure, prompt craft, efficiency, and more.",
+      "supports-headless": true,
+      "prompt": "quality-optimizer.md",
+      "phase-name": "anytime",
+      "output-location": "{bmad_builder_reports}"
+    }
+  ]
+}