[Bug] Local-scoped plugin installation blocks installation in other projects

Bug Description
Plugin installed with local scope for one project cannot be installed for another project

Description:
When a plugin is installed with scope: local for project A, attempting to install it for project B fails silently.

Steps to reproduce:

1. Install a plugin with local scope: /plugin install frontend-design@claude-plugins-official (from project A)
2. Navigate to a different project B
3. Run /plugin install frontend-design@claude-plugins-official
4. Get message: "Plugin is already installed"
5. But plugin doesn't appear in Installed tab (wrong scope)
6. Plugin also doesn't appear in Discover tab (already installed)
7. Clicking plugin in Marketplace list causes it to vanish and navigate to empty Installed tab

Expected behavior:

• Should offer to install for current project when already installed elsewhere with local scope
• OR should show in Installed tab with option to "Add to this project"

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.19
• Feedback ID: 228d7325-060b-4c56-9b88-9036228bcdd7

Errors

[{"error":"Error: ENOENT: no such file or directory, scandir '/Library/Application Support/ClaudeCode/.claude/skills'\n    at readdirSync (unknown)\n    at <anonymous> (/$bunfs/root/claude:12:1903)\n    at mW (/$bunfs/root/claude:11:35435)\n    at readdirSync (/$bunfs/root/claude:12:1864)\n    at ILR (/$bunfs/root/claude:2215:380)\n    at ILR (/$bunfs/root/claude:2215:1350)\n    at <anonymous> (/$bunfs/root/claude:2215:4440)\n    at <anonymous> (/$bunfs/root/claude:2215:5171)\n    at A (/$bunfs/root/claude:11:7259)\n    at FZ8 (/$bunfs/root/claude:4862:4342)","timestamp":"2026-01-27T02:52:55.655Z"},{"error":"Error: ENOENT: no such file or directory, scandir '/Library/Application Support/ClaudeCode/.claude/skills'\n    at readdirSync (unknown)\n    at <anonymous> (/$bunfs/root/claude:12:1903)\n    at mW (/$bunfs/root/claude:11:35435)\n    at readdirSync (/$bunfs/root/claude:12:1864)\n    at ILR (/$bunfs/root/claude:2215:380)\n    at ILR (/$bunfs/root/claude:2215:1350)\n    at <anonymous> (/$bunfs/root/claude:2215:4440)\n    at <anonymous> (/$bunfs/root/claude:2215:5171)\n    at A (/$bunfs/root/claude:11:7259)\n    at FZ8 (/$bunfs/root/claude:4862:4342)","timestamp":"2026-01-27T02:52:58.334Z"}]