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/services/ban_service.py

@@ -43,6 +43,7 @@ from app.models.ban import (
 from app.repositories import fail2ban_db_repo
 from app.repositories import history_archive_repo as default_history_archive_repo
 from app.services.fail2ban_metadata_service import default_fail2ban_metadata_service
+from app.utils.constants import DEFAULT_PAGE_SIZE, MAX_PAGE_SIZE
 from app.utils.fail2ban_client import (
     Fail2BanClient,
 )
@@ -72,8 +73,6 @@ async def get_fail2ban_db_path(socket_path: str) -> str:
 # Constants
 # ---------------------------------------------------------------------------
 
-_DEFAULT_PAGE_SIZE: int = 100
-_MAX_PAGE_SIZE: int = 500
 _SOCKET_TIMEOUT: float = 5.0
 
 
@@ -357,7 +356,7 @@ async def list_bans(
     *,
     source: str = "fail2ban",
     page: int = 1,
-    page_size: int = _DEFAULT_PAGE_SIZE,
+    page_size: int = DEFAULT_PAGE_SIZE,
     http_session: aiohttp.ClientSession | None = None,
     app_db: aiosqlite.Connection | None = None,
     geo_batch_lookup: GeoBatchLookup | None = None,
@@ -385,7 +384,7 @@ async def list_bans(
         range_: Time-range preset (``"24h"``, ``"7d"``, ``"30d"``, or
             ``"365d"``).
         page: 1-based page number (default: ``1``).
-        page_size: Maximum items per page, capped at ``_MAX_PAGE_SIZE``
+        page_size: Maximum items per page, capped at ``MAX_PAGE_SIZE``
             (default: ``100``).
         http_session: Optional shared :class:`aiohttp.ClientSession`.  When
             provided, :func:`~app.services.geo_service.lookup_batch` is used
@@ -403,7 +402,7 @@ async def list_bans(
     """
 
     since: int = _since_unix(range_)
-    effective_page_size: int = min(page_size, _MAX_PAGE_SIZE)
+    effective_page_size: int = min(page_size, MAX_PAGE_SIZE)
     offset: int = (page - 1) * effective_page_size
 
     if source not in ("fail2ban", "archive"):