Add template upload functionality to Schadenprotokoll

- New Templates tab for PDF and Word template management
- API endpoints for listing and uploading templates
- Automatic backup of old templates before replacement

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

schadenprotokoll/styles.css

@@ -105,3 +105,17 @@ header p { color: var(--text-muted); }
 .field-list { display: grid; gap: 0.5rem; }
 
 footer { text-align: center; margin-top: 3rem; color: var(--text-muted); font-size: 0.875rem; }
+
+.template-list { margin-bottom: 2rem; }
+.template-list h4 { margin-bottom: 1rem; }
+.template-item {
+    display: flex; justify-content: space-between; align-items: center;
+    padding: 1rem; background: white; border: 1px solid var(--border);
+    border-radius: 0.5rem; margin-bottom: 0.5rem;
+}
+.template-item .name { font-weight: 500; }
+.template-item .size { color: var(--text-muted); font-size: 0.875rem; }
+.template-upload h4 { margin-bottom: 1rem; }
+.upload-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
+.upload-zone.small { padding: 1.5rem; }
+.upload-zone.small h3 { font-size: 1rem; }