[BUG] list-plugins command unnecessarily initializes full Scanner

[KbWen]

Describe the Bug

In cli.py, the list-plugins command handler is placed inside the main try block (line 230-238) that occurs after the full Scanner initialization (line 193-199). This means running ghostcheck list-plugins unnecessarily:

1. Loads and instantiates all 34 security checker modules
2. Loads and parses the results cache from disk
3. Initializes baseline fingerprinting
4. Auto-detects framework presets

None of these are needed just to list available plugins.

Expected Behavior

ghostcheck list-plugins should be handled early in the CLI flow (similar to list-checks at line 164) to avoid unnecessary Scanner initialization overhead.

Proposed Fix

Move the list-plugins handler block to be adjacent to the list-checks handler (before Scanner initialization), using PluginManager directly instead of scanner.plugin_manager.

Impact

• Faster list-plugins execution (skip ~500ms of unnecessary init)
• No behavioral change for end users