Add CYD host PC info panel with serial SI protocol and LVGL bars.

ESP32 shows CPU/GPU/RAM/disk from host/send_sysinfo.ps1 over USB; firmware packages for 2.8 and 3.5 included.

Co-authored-by: Cursor <cursoragent@cursor.com>

include/host_info.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <stdint.h>
+
+/** Max chars for hostname / CPU / GPU name shown on UI. */
+static constexpr int HOST_NAME_MAX = 40;
+static constexpr int HOST_CPU_MAX = 48;
+static constexpr int HOST_GPU_MAX = 48;
+
+struct HostInfo {
+  char host[HOST_NAME_MAX];
+  char cpu[HOST_CPU_MAX];
+  char gpu[HOST_GPU_MAX];
+  float cpu_pct;      // 0..100
+  float gpu_pct;      // 0..100, -1 if unknown
+  float ram_used_gb;
+  float ram_total_gb;
+  float disk_used_gb;
+  float disk_total_gb;
+  bool valid;
+  uint32_t updated_ms;
+};
+
+void host_info_begin();
+/** Poll USB Serial for SI|... lines; return true if a packet was applied. */
+bool host_info_poll();
+const HostInfo &host_info_get();
+/** True if last packet is fresher than stale_ms. */
+bool host_info_is_live(uint32_t stale_ms = 5000);