fix: resolve Python FileNotFoundError and improve error handling

- Add proper error handling around temp_typst.unlink() in generate.py to prevent crashes when temp file doesn't exist
- Modify ServerSorobanSVG component to throw errors instead of showing fallback when backend fails

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

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

apps/web/src/components/ServerSorobanSVG.tsx

@@ -63,8 +63,7 @@ export function ServerSorobanSVG({
       } catch (err) {
         console.error(`Failed to generate SVG for ${number}:`, err)
         setError('Unable to generate SVG')
-        // Use fallback placeholder
-        setSvgContent(generateFallbackSVG(number, width, height))
+        throw new Error(`Failed to generate SVG for number ${number}: ${err instanceof Error ? err.message : 'Unknown error'}`)
       } finally {
         setIsLoading(false)
       }

packages/core/src/generate.py

@@ -415,7 +415,11 @@ def main():
             print(f"Generated: {output_path}")
             
             # Clean up temp file
-            temp_typst.unlink()
+            try:
+                temp_typst.unlink()
+            except FileNotFoundError:
+                # Temp file may have already been cleaned up or not created
+                pass
             
             # Add duplex printing hints and linearize if requested
             if args.linearize: