feat(logviewer): keep ~4x more history (1 MB tail)

The viewer fetched only the last 256 KB (~1600 lines) of opslog.log. During a
busy trace the oldest lines scrolled out of the window while the operator was
still reading them. Raise the tail to 1 MB (~6500 lines); the backend already
allows up to 4 MB.

frontend/src/components/LogViewer.tsx

@@ -21,7 +21,12 @@ import { TailLogFile, GetLogFilePath } from '../../wailsjs/go/main/App';
 //     256 KB blob: with "cluster" or "acom" typed in, the window becomes exactly
 //     the subsystem trace you would have grepped for.
 //   • It polls only while open. A closed dialog costs nothing.
-const TAIL_BYTES = 256 * 1024;
+// 1 MB ≈ 6500 lines. The window is a sliding tail: once new lines push past it
+// the oldest fall out of the fetched text entirely, so a small buffer dropped
+// lines the operator was still reading during a busy trace (CAT/cluster/antenna
+// polling). The backend caps this at 4 MB; 1 MB is a good balance against the
+// per-poll payload while open.
+const TAIL_BYTES = 1024 * 1024;
 const POLL_MS = 1000;
 
 export function LogViewer({ open, onOpenChange }: { open: boolean; onOpenChange: (v: boolean) => void }) {