feat: initial project structure

- GitLabClient: REST Events API z paginacją, pobieranie członków grupy
- Aggregator: zliczanie commitów, MR, komentarzy per użytkownik
- Exporter: generowanie pliku Excel (openpyxl) ze stylami
- main.py: CLI (click) + .env support
- README, .env.example, requirements.txt, .gitignore

aggregator.py

@@ -0,0 +1,69 @@
+"""
+Agregator — przetwarza eventy GitLab na statystyki per użytkownik.
+"""
+
+from collections import defaultdict
+from dataclasses import dataclass, field
+
+
+@dataclass
+class UserStats:
+    name: str = ""
+    username: str = ""
+    user_id: int = 0
+    commits: int = 0
+    merge_requests: int = 0
+    comments: int = 0
+    other: int = 0
+
+    @property
+    def total_contributions(self) -> int:
+        return self.commits + self.merge_requests + self.comments + self.other
+
+
+class Aggregator:
+    def __init__(self):
+        self._stats: dict[int, UserStats] = defaultdict(UserStats)
+
+    def process_events(self, events: list[dict]) -> None:
+        """
+        Przetwarza listę eventów GitLab i agreguje statystyki.
+
+        Typy akcji:
+          - pushed       → commit
+          - merged       → merge request
+          - commented    → komentarz
+          - created/closed/reopened → inne
+        """
+        for event in events:
+            author = event.get("author") or {}
+            uid = author.get("id") or event.get("author_id")
+            if not uid:
+                continue
+
+            stats = self._stats[uid]
+            stats.user_id = uid
+            stats.name = author.get("name", stats.name)
+            stats.username = author.get("username", stats.username)
+
+            action = event.get("action_name", "")
+
+            if action == "pushed to" or action == "pushed new":
+                # Liczymy commity z push events
+                push_data = event.get("push_data") or {}
+                commit_count = push_data.get("commit_count", 1)
+                stats.commits += max(commit_count, 1)
+            elif action in ("accepted", "merged"):
+                stats.merge_requests += 1
+            elif action == "commented on":
+                stats.comments += 1
+            else:
+                stats.other += 1
+
+    def get_stats(self) -> list[UserStats]:
+        """Zwraca listę statystyk posortowaną malejąco po contributions."""
+        return sorted(
+            self._stats.values(),
+            key=lambda s: s.total_contributions,
+            reverse=True,
+        )