Refactor backend services and routers

- Reorganized dashboard router with improved structure
- Enhanced ban_service with better separation of concerns
- Updated history service with cleaner logic
- Improved constants and configuration handling
- Updated documentation of completed tasks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/app/routers/history.py

@@ -28,11 +28,10 @@ from app.dependencies import (
 from app.models.ban import BanOrigin, TimeRange
 from app.models.history import HistoryListResponse, IpDetailResponse
 from app.services import history_service
+from app.utils.constants import DEFAULT_PAGE_SIZE
 
 router: APIRouter = APIRouter(prefix="/api/history", tags=["History"])
 
-_DEFAULT_PAGE_SIZE: int = 100
-
 
 @router.get(
     "",
@@ -67,7 +66,7 @@ async def get_history(
     ),
     page: int = Query(default=1, ge=1, description="1-based page number."),
     page_size: int = Query(
-        default=_DEFAULT_PAGE_SIZE,
+        default=DEFAULT_PAGE_SIZE,
         ge=1,
         le=500,
         description="Items per page (max 500).",
@@ -124,7 +123,7 @@ async def get_history_archive(
     jail: str | None = Query(default=None, description="Restrict results to this jail name."),
     ip: str | None = Query(default=None, description="Restrict results to IPs matching this prefix."),
     page: int = Query(default=1, ge=1, description="1-based page number."),
-    page_size: int = Query(default=_DEFAULT_PAGE_SIZE, ge=1, le=500, description="Items per page (max 500)."),
+    page_size: int = Query(default=DEFAULT_PAGE_SIZE, ge=1, le=500, description="Items per page (max 500)."),
 ) -> HistoryListResponse:
 
     return await history_service.list_history(