Switch dashboard/map/history views to archive source for long-term data

Update fail2ban dbpurgeage to 648000 and history sync backfill/pagination for archive-based 7.5 day history.

backend/app/routers/history.py

@@ -15,7 +15,7 @@ Routes
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Literal
 
 if TYPE_CHECKING:
     import aiohttp
@@ -56,7 +56,7 @@ async def get_history(
         default=None,
         description="Filter by ban origin: 'blocklist' or 'selfblock'. Omit for all.",
     ),
-    source: str = Query(
+    source: Literal["fail2ban", "archive"] = Query(
         default="fail2ban",
         description="Data source: 'fail2ban' or 'archive'.",
     ),