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

skills/memory-management/SKILL.md

@@ -0,0 +1,31 @@
+---
+name: memory-management
+description: How Claude Memory manages persistent memory across sessions and compactions
+---
+
+# Memory Management
+
+## Available MCP Tools
+- `memory_store`: Save facts, preferences, decisions
+- `memory_recall`: Retrieve relevant memories by context
+- `memory_list`: List recent memories
+- `memory_delete`: Delete a memory by ID
+- `secret_get`: Retrieve decrypted content of a sensitive memory
+
+## When to Store Memories
+- User says "remember X" -> store immediately
+- User shares preferences -> store with category "preferences"
+- Important project context -> store with category "projects"
+- Key decisions -> store with category "decisions"
+- People details -> store with category "people"
+
+## When to Recall Memories
+- Before answering preference questions ("how do I like X?")
+- When user references past conversations
+- At session start (memories are injected via compaction recovery)
+
+## Compaction Survival
+Memory survives context compactions via:
+1. PreCompact hook saves key memories to a marker file
+2. UserPromptSubmit hook detects the marker and injects recovery context
+3. SQLite database persists across all sessions