feat: add Dashboard tab with live GPU overview

Add a new Dashboard tab as the default/first tab (Dashboard - Curve -
Performance - Fans) showing a full GPU overview.

Backend:
- New hal/dashboard.py: one-shot static GPU info via NVML (VBIOS, CUDA
  cores, compute capability, bus width, BAR1/CPU-accessible VRAM,
  Resizable BAR, PCIe max, max clocks, power limits, temp thresholds,
  persistence mode, fan count, serial, board part number, UUID).
  ROP count and VRAM type are best-effort from a per-model table since
  NVML does not expose them.
- New /api/dashboard endpoint.
- MonitoringSample gains live throttle_reasons (+label), PCIe link
  width/generation (downclocks when idle, so read per poll), and VRAM
  temp (from the MEMORY thermal sensor, if exposed).

Frontend:
- New Dashboard component: critical top row (throttling, voltage,
  GPU/VRAM temps), full live-monitor grid with sparklines, and a static
  GPU-information grid. Unavailable fields are omitted.
- useDashboard hook + DashboardInfo type + api.client dashboard().

Also: restrict CORS to localhost origins (end-anchored), make
_int_key_deltas fail closed on bad keys, and clean up lint blockers in
server.py/monitoring.py.

frontend/src/hooks/useDashboard.ts

@@ -0,0 +1,47 @@
+import { useEffect, useState } from "react";
+import { api } from "../api/client";
+import { useCurveStore } from "../store/curveStore";
+import type { DashboardInfo } from "../types";
+
+interface DashboardState {
+  gpuIndex: number;
+  data: DashboardInfo | null;
+  done: boolean;
+}
+
+/**
+ * Fetch static GPU info for the Dashboard tab.
+ * Re-fetches when the selected GPU changes.
+ */
+export function useDashboard() {
+  const { selectedGpuIndex } = useCurveStore();
+  const [state, setState] = useState<DashboardState>({
+    gpuIndex: -1,
+    data: null,
+    done: false,
+  });
+
+  useEffect(() => {
+    let cancelled = false;
+    api
+      .dashboard(selectedGpuIndex)
+      .then((data) => {
+        if (!cancelled)
+          setState({ gpuIndex: selectedGpuIndex, data, done: true });
+      })
+      .catch((err) => {
+        console.error("Failed to load dashboard info:", err);
+        if (!cancelled)
+          setState({ gpuIndex: selectedGpuIndex, data: null, done: true });
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [selectedGpuIndex]);
+
+  const isCurrent = state.gpuIndex === selectedGpuIndex;
+  return {
+    dashboard: isCurrent ? state.data : null,
+    loading: !isCurrent || !state.done,
+  };
+}