Plugin shows as 'installed' globally when only installed locally in one project

Description

When a plugin is installed with scope: "local" in a specific project directory, the plugin browser UI shows it as "(installed)" in all directories, not just the one where it's actually installed and active.

Steps to Reproduce

1. Navigate to a specific project directory
2. Install a plugin (e.g., Notion) using /plugin install notion
3. The plugin is installed with scope: "local" for that directory only
4. Navigate to a different directory
5. Open /plugin browser
6. The plugin shows as "(installed)" even though it's not available in this directory

Expected Behavior

• Plugin should only show as "installed" in the directory where it was installed locally
• OR the UI should indicate "installed (local)" to clarify it's not globally available
• OR the plugin should appear under "Installed" plugins section if it shows "(installed)" in the browse list

Actual Behavior

• Plugin shows "(installed)" in all directories
• Plugin does NOT appear under "Installed" plugins section
• Plugin is only actually active in the original installation directory

Evidence

~/.claude/plugins/installed_plugins.json shows:

"Notion@claude-plugins-official": [
    {
        "scope": "local",
        "projectPath": "/path/to/specific/project",
        ...
    }
]

But the browse plugins UI shows "(installed)" regardless of current directory.

Environment

• macOS
• Claude Code (latest version)