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/dashboard.py

@@ -35,6 +35,7 @@ from app.models.ban import (
 )
 from app.models.server import ServerStatus, ServerStatusResponse
 from app.services import ban_service, geo_service
+from app.utils.constants import DEFAULT_PAGE_SIZE
 
 router: APIRouter = APIRouter(prefix="/api/dashboard", tags=["Dashboard"])
 
@@ -42,7 +43,6 @@ router: APIRouter = APIRouter(prefix="/api/dashboard", tags=["Dashboard"])
 # Default pagination constants
 # ---------------------------------------------------------------------------
 
-_DEFAULT_PAGE_SIZE: int = 100
 _DEFAULT_RANGE: TimeRange = "24h"
 
 
@@ -91,7 +91,7 @@ async def get_dashboard_bans(
         description="Data source: 'fail2ban' or 'archive'.",
     ),
     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."),
+    page_size: int = Query(default=DEFAULT_PAGE_SIZE, ge=1, le=500, description="Items per page."),
     origin: BanOrigin | None = Query(
         default=None,
         description="Filter by ban origin: 'blocklist' or 'selfblock'. Omit for all.",