fix: implement stream recovery to prevent chat hanging

[embire2]

Description

This PR implements a minimal solution to prevent chat conversations from hanging when the AI stream becomes unresponsive.

Problem

Users experience hanging chat conversations when:

• The AI stream becomes unresponsive
• Network issues cause stream interruptions
• API timeouts occur without proper handling

Solution

Implemented a lightweight StreamRecoveryManager that:

• Monitors stream activity with 45-second timeout
• Automatically attempts recovery (2 retries)
• Provides proper cleanup on stream completion
• Logs timeout events for debugging

Changes (2 files only)

1. app/lib/.server/llm/stream-recovery.ts (new file, 92 lines)

   • StreamRecoveryManager class
   • Timeout detection and recovery logic

2. app/routes/api.chat.ts (15 line additions)

   • Import StreamRecoveryManager
   • Initialize recovery manager
   • Start monitoring on stream execute
   • Update activity in stream loop
   • Stop monitoring on completion

Testing

✅ Tested with various AI models
✅ Verified timeout detection works
✅ Confirmed proper cleanup
✅ Normal conversations unaffected

Impact

• Minimal: Only 2 files, 107 lines total
• Non-breaking: Backward compatible
• Performance: Negligible overhead

Fixes #1964

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Author: Keoma Wright

[Stijnus]

Thank you , Good job!