Fix concurrent access issues causing Bad Gateway errors

[BenCretois]

Major improvements for multi-user access:

Root Cause Analysis:

• Streamlit @st.cache_data with _self parameter was causing cache key conflicts
• Shared temporary file dictionary caused resource conflicts between sessions
• No proper session isolation for concurrent users

Solutions Implemented:

1. Enhanced Cache Isolation:

   • Added unique cache keys based on file paths and parameters
   • Maintains instance method pattern while fixing cache conflicts
   • Each user session gets properly isolated cache entries

2. Session-Specific Temp Files:

   • Added session-specific prefixes for temporary files
   • Prevents file conflicts between concurrent users
   • Auto-cleanup remains intact per session

3. Session Management:

   • Added UUID-based session IDs in main app
   • Improved Streamlit configuration for concurrent users
   • Better connection handling and caching settings

4. Service Layer Fixes:

   • Fixed DataService, AudioService, and SiteMetadataService
   • Maintained backward compatibility with existing API
   • Proper error handling for concurrent operations

Configuration Updates:

• Enhanced .streamlit/config.toml for better concurrent handling
• Disabled usage stats to reduce potential race conditions
• Improved message size and upload limits

Impact:

• ✅ Eliminates Bad Gateway errors when multiple users access dashboard
• ✅ Each user session is properly isolated
• ✅ Maintains all existing functionality
• ✅ Better performance under concurrent load
• ✅ Backward compatible API

The dashboard now supports multiple concurrent users without conflicts!