Add missing repository components for complete supercharge.sh installation

Added all directories and files expected by supercharge.sh:

- hooks/ (5 hook scripts for session management and AI consultation)
- commands/ (3 custom slash commands: brainstorm, write-plan, execute-plan)
- plugins/ (plugin references for glm-plan, rust-analyzer, marketplaces)
- bin/ralphloop (Ralph Orchestrator wrapper for autonomous iteration)
- scripts/sync-agents.sh (agent synchronization script)
- templates/ (config templates: settings, hooks, config.json)

This completes the repository structure so supercharge.sh can install
all components without warnings.

Co-Authored-By: Claude <noreply@anthropic.com>

plugins/marketplaces/README.md

@@ -0,0 +1,30 @@
+# Plugin Marketplace
+
+References to external plugin marketplaces for Claude Code.
+
+## Available Marketplaces
+
+### Superpowers Marketplace
+- **URL**: https://github.com/obra/superpowers-marketplace
+- **Description**: Community-driven skills and plugins marketplace
+- **Install**: Add to `config.json` marketplaces section
+
+## Installation
+
+To add a marketplace, edit `~/.claude/config.json`:
+
+```json
+{
+  "marketplaces": {
+    "obra/superpowers-marketplace": "/path/to/marketplace"
+  }
+}
+```
+
+## Featured Plugins
+
+Browse the marketplace to discover:
+- Custom skills
+- Agent templates
+- Tool integrations
+- Theme packages