refactor(plugin): move plugin.json to root directory

- Move plugin.json from .claude-plugin/ to root
- Add marketplace.json for plugin discovery

Author: zircote

.claude-plugin/marketplace.json

@@ -0,0 +1,25 @@
+{
+  "name": "git-notes-memory",
+  "description": "Plugin marketplace for git-notes-memory - Git-native, semantically-searchable memory storage for Claude Code",
+  "version": "1.0.0",
+  "owner": {
+    "name": "zircote",
+    "email": "zircote@gmail.com"
+  },
+  "plugins": [
+    {
+      "name": "memory-capture",
+      "description": "Git-backed memory system for Claude Code. Captures decisions, learnings, and context as git notes with semantic search and automatic recall.",
+      "version": "0.1.0",
+      "author": {
+        "name": "Robert Allen",
+        "email": "zircote@gmail.com"
+      },
+      "repository": "https://github.com/zircote/git-notes-memory-manager",
+      "license": "MIT",
+      "keywords": ["memory", "git-notes", "semantic-search", "context", "recall"],
+      "source": "./",
+      "homepage": "https://github.com/zircote/git-notes-memory-manager#readme"
+    }
+  ]
+}

.claude-plugin/plugin.json

@@ -0,0 +1,16 @@
+{
+  "name": "memory-capture",
+  "version": "0.1.0",
+  "description": "Git-backed memory system for Claude Code. Captures decisions, learnings, and context as git notes with semantic search and automatic recall.",
+  "author": {
+    "name": "Robert Allen",
+    "email": "zircote@gmail.com"
+  },
+  "homepage": "https://github.com/zircote/git-notes-memory-manager#readme",
+  "repository": "https://github.com/zircote/git-notes-memory-manager",
+  "license": "MIT",
+  "keywords": ["memory", "git-notes", "semantic-search", "context", "recall"],
+  "commands": "./commands/",
+  "skills": "./skills/",
+  "hooks": "./hooks/hooks.json"
+}