2931 Fix Log Service Critical 394dc938

# Critical Fix - LogService Missing is_stream Field

## Problem Found ✅

You were absolutely correct! The database had `is_stream` correctly stored, but the **API was returning `false` for all requests**.

### Root Cause

The `LogService.query()` method (at `backend/app/services/log_service.py`) was manually constructing `RequestLogResponse` objects from `RequestLogModel` objects, but it was **missing the `is_stream` field in the mapping**.

### The Bug

```python
# In LogService.query() - line 84-100
responses = [
    RequestLogResponse(
        id=log.id,
        request_time=log.request_time,
        # ... all other fields ...
        trace_id=log.trace_id,
        # ❌ is_stream=log.is_stream,  <-- THIS WAS MISSING!
    )
    for log in logs
]
```

Because `is_stream` wasn't explicitly passed, Pydantic used the default value from `RequestLogResponse` which is `False`.

### The Fix

Added the missing line:

```python
responses = [
    RequestLogResponse(
        id=log.id,
        # ... all other fields ...
        trace_id=log.trace_id,
        is_stream=log.is_stream,  # ✅ ADDED THIS LINE
    )
    for log in logs
]
```

## Complete Data Flow - Now Fixed ✅

1. ✅ **Request comes in** → `app/api/proxy/openai.py` detects `stream=true`
2. ✅ **Proxy service** → Sets `is_stream=True` in log data
3. ✅ **Repository writes** → Saves to database with `is_stream=1`
4. ✅ **Repository reads** → Retrieves `is_stream` from database
5. ✅ **Service returns** → **NOW INCLUDES `is_stream` in API response** ← **THIS WAS BROKEN**
6. ✅ **Frontend displays** → Shows wave icon based on `is_stream` value

## Files Modified (All Commits)

### Commit 1: Core Implementation
- `backend/app/db/models.py` - Database schema
- `backend/app/domain/log.py` - Domain models
- `backend/app/services/proxy_service.py` - Set is_stream flag
- `frontend/src/types/log.ts` - Frontend types
- `frontend/src/components/logs/LogList.tsx` - UI display
- `backend/migrations/` - Migration scripts

### Commit 2: Repository Fix
- `backend/app/repositories/sqlalchemy/log_repo.py` - Read/write is_stream

### Commit 3: Documentation
- `TROUBLESHOOTING_STREAM_DISPLAY.md`
- `STREAM_FEATURE_COMPLETE.md`
- `backend/check_migration.py`

### Commit 4: Service Layer Fix (CRITICAL)
- `backend/app/services/log_service.py` - **Include is_stream in API response**

## Testing After Fix

After restarting the backend, the API should now return:

```json
{
  "items": [
    {
      "id": 123,
      "is_stream": true,  // ← Now correctly reflects database value!
      "request_time": "...",
      ...
    }
  ]
}
```

## Why This Was Hard to Find

The bug was subtle because:
1. ✅ Database was storing correctly
2. ✅ Repository was reading correctly  
3. ❌ **Service layer was dropping the field when converting to response**
4. ✅ Frontend was working correctly (just displaying what API returned)

The service layer was manually mapping fields instead of using `.model_dump()` or `**log.dict()`, so the new field needed to be explicitly added to the mapping.

## Action Required

**Restart the backend** and the stream display should work immediately!

No database migration needed if you already have the `is_stream` column - the data is already there, it just wasn't being returned by the API.