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/dashboard.py

@@ -24,6 +24,7 @@ from app.dependencies import (
     GeoCacheDep,
     HttpSessionDep,
     ServerStatusDep,
+    SettingsDep,
 )
 from app.mappers import (
     map_domain_ban_trend_to_response,
@@ -101,13 +102,14 @@ async def get_dashboard_bans(
     socket_path: Fail2BanSocketDep,
     http_session: HttpSessionDep,
     geo_cache: GeoCacheDep,
+    settings: SettingsDep,
     range: TimeRange = Query(default=_DEFAULT_RANGE, description="Time-range preset."),
     source: Literal["fail2ban", "archive"] = Query(
         default="fail2ban",
         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, description="Items per page."),
     origin: BanOrigin | None = Query(
         default=None,
         description="Filter by ban origin: 'blocklist' or 'selfblock'. Omit for all.",
@@ -143,6 +145,7 @@ async def get_dashboard_bans(
         source=source,
         page=page,
         page_size=page_size,
+        max_page_size=settings.max_page_size,
         http_session=http_session,
         app_db=ban_ctx.db,
         geo_cache=geo_cache,