feat: comprehensive health check with DB, scheduler, cache

- Add /api/v1/health endpoint with component-level checks
- Verify DB connectivity, fail2ban socket, scheduler, session cache
- Add SQLite WAL cleanup on startup (orphan crash files)
- Migration 8: import_log.timestamp → INTEGER UNIX epoch
- Align import_log timestamps with history_archive (already UNIX int)
- Add unit tests for DB cleanup and health router

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

frontend/src/components/blocklist/BlocklistImportLogSection.tsx

@@ -3,6 +3,11 @@ import { ArrowClockwiseRegular } from "@fluentui/react-icons";
 import { useCommonSectionStyles } from "../../components/commonStyles";
 import { useImportLog } from "../../hooks/useImportLog";
 import { useBlocklistStyles } from "./blocklistStyles";
+import { formatDate } from "../../utils/formatDate";
+
+function formatUnixTimestamp(unixTs: number, timezone: string | null | undefined): string {
+  return formatDate(new Date(unixTs * 1000).toISOString(), timezone);
+}
 
 export function BlocklistImportLogSection(): React.JSX.Element {
   const styles = useBlocklistStyles();
@@ -52,7 +57,7 @@ export function BlocklistImportLogSection(): React.JSX.Element {
                   <TableRow key={entry.id} className={entry.errors ? styles.errorRow : undefined}>
                     <TableCell>
                       <TableCellLayout>
-                        <span className={styles.mono}>{entry.timestamp}</span>
+                        <span className={styles.mono}>{formatUnixTimestamp(entry.timestamp, undefined)}</span>
                       </TableCellLayout>
                     </TableCell>
                     <TableCell>

frontend/src/types/blocklist.ts

@@ -41,7 +41,7 @@ export interface ImportLogEntry {
   id: number;
   source_id: number | null;
   source_url: string;
-  timestamp: string;
+  timestamp: number;
   ips_imported: number;
   ips_skipped: number;
   errors: string | null;