refactor(backend): clean up jail service, add error handling service

- Extract jail status/processing to helper functions
- Add error_handling.py service for centralized error handling
- Update config.py with validation and defaults
- Update .env.example with all config options
- Remove obsolete Tasks.md, add Service-Development.md
- Minor fixes across routers and services

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

backend/app/routers/history.py

@@ -25,6 +25,7 @@ from app.dependencies import (
     Fail2BanSocketDep,
     HistoryServiceContextDep,
     HttpSessionDep,
+    SettingsDep,
 )
 from app.exceptions import HistoryNotFoundError
 from app.mappers import history_mappers
@@ -54,6 +55,7 @@ async def get_history(
     socket_path: Fail2BanSocketDep,
     http_session: HttpSessionDep,
     fail2ban_metadata_service: Fail2BanMetadataServiceDep,
+    settings: SettingsDep,
     range: TimeRange | None = Query(
         default=None,
         description="Optional time-range filter. Omit for all-time.",
@@ -78,8 +80,7 @@ async def get_history(
     page_size: int = Query(
         default=DEFAULT_PAGE_SIZE,
         ge=1,
-        le=500,
-        description="Items per page (max 500).",
+        description="Items per page.",
     ),
 ) -> HistoryListResponse:
     """Return a paginated list of historical bans with optional filters.
@@ -114,6 +115,7 @@ async def get_history(
         source=source,
         page=page,
         page_size=page_size,
+        max_page_size=settings.max_page_size,
         http_session=http_session,
         db=history_ctx.db,
         fail2ban_metadata_service=fail2ban_metadata_service,
@@ -138,6 +140,7 @@ async def get_history_archive(
     socket_path: Fail2BanSocketDep,
     http_session: HttpSessionDep,
     fail2ban_metadata_service: Fail2BanMetadataServiceDep,
+    settings: SettingsDep,
     range: TimeRange | None = Query(
         default=None,
         description="Optional time-range filter. Omit for all-time.",
@@ -145,7 +148,7 @@ 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, description="Items per page."),
 ) -> HistoryListResponse:
 
     domain_result = await history_service.list_history(
@@ -156,6 +159,7 @@ async def get_history_archive(
         source="archive",
         page=page,
         page_size=page_size,
+        max_page_size=settings.max_page_size,
         http_session=http_session,
         db=history_ctx.db,
         fail2ban_metadata_service=fail2ban_metadata_service,