1889 Public Workspace Storage Calculation Fix 20807ba7

# Public Workspace Storage Calculation Fix

**Fixed/Implemented in version: 0.230.082**

## Issue Description

Public workspaces were showing 0 bytes for storage sizes despite having documents, while group workspaces correctly calculated storage sizes from Azure Storage blobs.

## Root Cause Analysis

After fixing the field name issue (`public_workspace_id` vs `workspace_id`) in version 0.230.081, document counts were working correctly but storage calculations had several issues:

### Problems Identified:

1. **Incorrect folder prefix**: Public workspaces used `public/{workspace_id}/` but actual Azure Storage structure uses `{workspace_id}/`
2. **Inadequate fallback logic**: Public workspaces had basic fallback, but groups had sophisticated file-type based estimation
3. **Inconsistent error handling**: Public workspaces lacked the robust error handling that groups had
4. **Missing debug logging**: Insufficient debugging information for storage calculation issues

## Technical Solution

### Files Modified:
- `route_backend_control_center.py`: Updated public workspace storage calculation logic

### Changes Implemented:

1. **Fixed Folder Prefix**
   ```python
   # Before (incorrect)
   workspace_folder_prefix = f"public/{workspace_id}/"
   
   # After (matches actual storage structure)
   workspace_folder_prefix = f"{workspace_id}/"
   ```

2. **Enhanced Fallback Logic**
   ```python
   # Before: Simple sum query
   SELECT VALUE SUM(c.storage_account_size) FROM c 
   
   # After: File-type based estimation (matching groups)
   SELECT c.file_name, c.number_of_pages FROM c
   # Then estimate based on file type:
   # - PDF: ~500KB per page
   # - Word: ~300KB per page  
   # - PowerPoint: ~800KB per page
   # - Other: ~400KB per page
   ```

3. **Improved Error Handling**
   ```python
   # Before: Basic error logging
   debug_print(f"Error calculating storage...")
   
   # After: Robust error handling with fallback
   except Exception as storage_e:
       debug_print(f"❌ Storage calculation failed...")
       enhanced['activity']['document_metrics']['storage_account_size'] = 0
       enhanced['storage_size'] = 0
   ```

4. **Enhanced Debug Logging**
   - Added blob enumeration logging
   - Fallback estimation progress logging
   - Consistent debug markers matching group patterns

## Impact Assessment

### Before Fix:
- ❌ Public workspace storage always showed 0 B
- ❌ No fallback when Azure Storage client unavailable  
- ❌ Poor error handling caused calculation failures
- ❌ Minimal debug information for troubleshooting

### After Fix:
- ✅ Public workspaces calculate actual storage sizes from Azure Storage
- ✅ Intelligent fallback estimation when storage client unavailable
- ✅ Robust error handling prevents crashes
- ✅ Comprehensive debug logging for troubleshooting

## Technical Details

### Storage Container Structure:
```
public-documents container:
├── {workspace-id-1}/
│   ├── document1.pdf
│   └── document2.docx
├── {workspace-id-2}/
│   └── document3.pptx
└── {workspace-id-3}/
    ├── document4.txt
    └── document5.pdf
```

### Calculation Logic:
1. **Primary**: Enumerate blobs in `{workspace_id}/` folder, sum actual blob sizes
2. **Fallback**: Query document metadata, estimate sizes based on file type and page count
3. **Error**: Set storage size to 0 to prevent display issues

### File Size Estimations:
- **PDF files**: 500KB × number_of_pages
- **Word documents**: 300KB × number_of_pages
- **PowerPoint**: 800KB × number_of_pages
- **Other files**: 400KB × number_of_pages

## Testing and Validation

### Test Coverage:
- Storage client retrieval and blob enumeration
- Folder prefix correction validation
- Fallback estimation logic verification
- Error handling robustness testing
- Container usage consistency checking

### Validation Results:
- ✅ Folder prefix matches actual Azure Storage structure
- ✅ Fallback logic identical to proven group implementation
- ✅ Error handling prevents crashes and provides graceful degradation
- ✅ Debug logging enables effective troubleshooting

## Expected Behavior Changes

### Control Center Display:
Before:
```
HR          | Total Docs: 2 | AI Search: 880 KB | Storage: 0 B
IT          | Total Docs: 1 | AI Search: 160 KB | Storage: 0 B  
Service Desk| Total Docs: 4 | AI Search: 1.41 MB| Storage: 0 B
```

After:
```
HR          | Total Docs: 2 | AI Search: 880 KB | Storage: 1.2 MB
IT          | Total Docs: 1 | AI Search: 160 KB | Storage: 450 KB
Service Desk| Total Docs: 4 | AI Search: 1.41 MB| Storage: 2.8 MB
```

### Debug Output:
Enhanced logging provides clear insight into storage calculation:
```
💾 [PUBLIC WORKSPACE STORAGE DEBUG] Looking for blobs with prefix: dfbd222c-1aea-44c3-b1ac-6d9b7742682c/
💾 [PUBLIC WORKSPACE STORAGE DEBUG] Found 4 blobs, total size: 2847362 bytes
💾 [PUBLIC WORKSPACE STORAGE DEBUG] Fallback estimation complete: 2400000 bytes
```

## Related Issues

This fix completes the public workspace metrics consistency work started in version 0.230.080-081:
- 0.230.080: Implemented caching consistency
- 0.230.081: Fixed field name consistency (`public_workspace_id`)
- 0.230.082: Fixed storage calculation consistency

Public workspaces now have complete feature parity with group workspaces for document metrics calculation and caching.