feat: Claude Code plugin structure (#39)

* feat: add Claude Code plugin structure, move skills to root

Move skills from src/skills/ to skills/ at repo root and add
.claude-plugin/ manifest for Claude Code plugin and Vercel Skills
CLI compatibility. Three distribution paths now supported:
- claude plugin install (Claude Code native)
- npx skills add (43-agent skills ecosystem)
- npx bmad-method install (BMad Method installer)

BREAKING: src/ directory removed. Module definition path changes
from src/module.yaml to skills/module.yaml (requires bmm update).

* style: fix prettier formatting in plugin manifests

* fix: update markdownlint ignore path for skills/ move

Author: bmadcode

.claude-plugin/marketplace.json

@@ -0,0 +1,15 @@
+{
+  "name": "bmad-builder",
+  "owner": {
+    "name": "Brian (BMad) Madison"
+  },
+  "plugins": [
+    {
+      "name": "bmad-builder",
+      "source": "./",
+      "description": "BMad AI agent and workflow factory — build, edit, optimize, and validate agents and workflows through conversational discovery.",
+      "version": "1.1.0",
+      "skills": ["./skills/bmad-agent-builder", "./skills/bmad-builder-setup", "./skills/bmad-workflow-builder"]
+    }
+  ]
+}

.claude-plugin/plugin.json

@@ -0,0 +1,12 @@
+{
+  "name": "bmad-builder",
+  "version": "1.1.0",
+  "description": "Build AI agents and workflows from a conversation. Three skills — Agent Builder, Workflow Builder, and Setup — guide you from idea to production-ready skill structure with built-in quality optimization. Part of the BMad Method ecosystem.",
+  "author": {
+    "name": "Brian (BMad) Madison"
+  },
+  "license": "MIT",
+  "homepage": "https://github.com/bmad-code-org/bmad-builder",
+  "repository": "https://github.com/bmad-code-org/bmad-builder",
+  "keywords": ["bmad", "agent-builder", "workflow-builder", "skill-factory", "ai-agents"]
+}

.markdownlint-cli2.yaml

@@ -7,7 +7,7 @@ ignores:
   - CODE_OF_CONDUCT.md
   - _bmad/**
   - _bmad*/**
-  - src/skills/**
+  - skills/**
   - .*/**
   - z*/**
 

package.json

@@ -15,7 +15,8 @@
   "type": "module",
   "main": "",
   "files": [
-    "src/",
+    "skills/",
+    ".claude-plugin/",
     "CHANGELOG.md"
   ],
   "scripts": {