Add Claude Code plugin scaffold for single-repo install

Consolidates plugin components (hooks, commands, skills, MCP config)
into this repo so it can be installed with:
  claude plugins install github:ViktorBarzin/claude-memory-mcp

- .claude-plugin/plugin.json: manifest with all hook events
- mcp/memory-mcp.json: MCP server config using existing src/
- hooks/: compaction survival, auto-recall, auto-learn, auto-approve
- commands/: /remember and /recall slash commands
- skills/: memory-management skill
- Bump MCP server to v2.0.0 with metaclaw migration fallback
- Update README with quick install and plugin hooks docs

mcp/memory-mcp.json

@@ -0,0 +1,14 @@
+{
+  "mcpServers": {
+    "claude_memory": {
+      "type": "stdio",
+      "command": "python3",
+      "args": ["${CLAUDE_PLUGIN_ROOT}/src/claude_memory/mcp_server.py"],
+      "env": {
+        "MEMORY_API_URL": "${MEMORY_API_URL}",
+        "MEMORY_API_KEY": "${MEMORY_API_KEY}",
+        "PYTHONPATH": "${CLAUDE_PLUGIN_ROOT}/src"
+      }
+    }
+  }
+}