Bug: installed_plugins.json shows incorrect plugin version from marketplace

Bug Description

The installed_plugins.json file shows an outdated version for a plugin installed from marketplace, even though the actual installed version is newer.

Steps to Reproduce

1. Install claude-mem plugin from thedotmack marketplace
2. Check version in installed_plugins.json
3. Compare with actual version in marketplace directory

Expected Behavior

• installed_plugins.json should reflect the actual installed plugin version

Actual Behavior

• installed_plugins.json shows version 4.3.0
• Actual installed plugin version in marketplace is 5.4.0
• This creates confusion about which version is actually running

Environment

• Platform: Linux
• Claude Code version: latest
• Plugin: claude-mem@thedotmack

Additional Context

~/.claude/plugins/installed_plugins.json:

"claude-mem@thedotmack": {
  "version": "4.3.0",  // ❌ Incorrect
  ...
}

~/.claude/plugins/marketplaces/thedotmack/plugin/.claude-plugin/plugin.json:

{
  "name": "claude-mem",
  "version": "5.4.0",  // ✅ Correct
  ...
}

This suggests the version in installed_plugins.json is not being updated when marketplace plugins are updated.