Add detailed skip tracking for phone imports

- Track skipped_no_phone and skipped_no_id separately
- Display skip information in admin UI with warning icon
- Clarify that empty phone numbers cannot be imported (PK constraint)
- Update documentation to explain expected skip behavior
- Example: 143 rows without phone numbers is correct, not an error

When importing PHONE.csv with empty phone numbers:
- Rows are properly skipped (cannot have NULL in primary key)
- User sees: '⚠️ Skipped: 143 rows without phone number'
- This is expected behavior, not a bug

app/main.py

@@ -1133,7 +1133,7 @@ def run_auto_import_for_upload(db: Session, uploaded_items: List[Dict[str, Any]]
             import_log.completed_at = datetime.now()
             db.commit()
 
-            files_summary.append({
+            summary_item = {
                 "filename": item.get("filename"),
                 "stored_filename": stored_filename,
                 "import_type": import_type,
@@ -1142,7 +1142,18 @@ def run_auto_import_for_upload(db: Session, uploaded_items: List[Dict[str, Any]]
                 "success_count": result.get("success", 0),
                 "error_count": len(result.get("errors", [])),
                 "errors": (result.get("errors", [])[:10] if result.get("errors") else []),
-            })
+            }
+            
+            # Add skip details if present (for phone imports and others that track this)
+            if result.get("skipped_no_phone", 0) > 0 or result.get("skipped_no_id", 0) > 0:
+                skip_details = []
+                if result.get("skipped_no_phone", 0) > 0:
+                    skip_details.append(f"{result['skipped_no_phone']} rows without phone number")
+                if result.get("skipped_no_id", 0) > 0:
+                    skip_details.append(f"{result['skipped_no_id']} rows without ID")
+                summary_item["skip_info"] = ", ".join(skip_details)
+            
+            files_summary.append(summary_item)
 
             if result.get("errors"):
                 stopped = True