Fix community settings page 500 error - missing platform config loading

## Problem Fixed:
The /settings/communities page was throwing a 500 error with:
`NameError: name 'platform_config' is not defined`

## Root Cause:
In the settings_communities() function, I was trying to use platform_config
without loading it first using the load_platform_config() function.

## Solution:
Added platform_config = load_platform_config() before using the variable.

This fixes the 500 error when users try to access community settings.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

app.py

@@ -1399,6 +1399,9 @@ def settings_communities():
     # Get available communities from platform config and collection targets
     available_communities = []
     
+    # Load platform configuration
+    platform_config = load_platform_config()
+    
     # Get enabled communities from collection_targets (what's actually being crawled)
     enabled_communities = set()
     for target in platform_config.get('collection_targets', []):