feat: JSON, Excel export and time summary

- #23: add JSONFormatter and XLSXFormatter
- add openpyxl dependency for .xlsx export
- #22: add --summary flag and calculate_summary() in report_builder
- ReportRow now carries raw hours for summary calculations
- update CLI help and README with .json/.xlsx formats and --summary
- add tests for new formatters and summary computation

Closes #22, closes #23

redmine_reporter/report_builder.py

@@ -63,6 +63,7 @@ def build_grouped_report(
                     "subject": issue.subject,
                     "status_ru": status_ru,
                     "time_text": time_text,
+                    "hours": round(hours, 2),
                 },
             )
         )
@@ -73,6 +74,26 @@ def build_grouped_report(
     return rows
 
 
+def calculate_summary(rows: List[ReportRow]) -> Dict[str, float]:
+    """Возвращает сводку: общее время, время по проектам и версиям."""
+    total = 0.0
+    by_project: Dict[str, float] = {}
+    by_project_version: Dict[str, float] = {}
+
+    for r in rows:
+        hours = r.get("hours", 0.0)
+        total += hours
+        by_project[r["project"]] = by_project.get(r["project"], 0.0) + hours
+        key = f"{r['project']}::{r['version']}"
+        by_project_version[key] = by_project_version.get(key, 0.0) + hours
+
+    return {
+        "total": round(total, 2),
+        **{f"project:{k}": round(v, 2) for k, v in by_project.items()},
+        **{f"version:{k}": round(v, 2) for k, v in by_project_version.items()},
+    }
+
+
 def group_rows_by_project_and_version(
     rows: List[ReportRow],
 ) -> Dict[str, Dict[str, List[ReportRow]]]: