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/api/client.ts

@@ -7,6 +7,7 @@ import type {
   ProfileData,
   FanState,
   FanPoint,
+  DashboardInfo,
 } from "../types";
 
 export class ApiError extends Error {
@@ -108,6 +109,7 @@ export const api = {
 
   gpus: () => get<GpuInfo[]>("/gpus"),
   gpu: (gpuIndex: number) => get<GpuInfo>("/gpu", gpuIndex),
+  dashboard: (gpuIndex: number) => get<DashboardInfo>("/dashboard", gpuIndex),
   curve: (gpuIndex: number) => get<CurveState>("/curve", gpuIndex),
   ranges: (gpuIndex: number) =>
     get<Record<string, { min_khz: number; max_khz: number }>>(