system-monitor: CPU temperature in bTop (Temperature card under Memory)

- Backend: readTemps() scans /sys/class/hwmon for all temp sensors and picks the
  CPU one (k10temp/coretemp/zenpower Tctl/Tdie/Package); added to /stats.temp.
- BtopView: a Temperature card at lg:col-start-2 (under Memory, second row) —
  big CPU °C (color-graded), its sensor label, and the other sensors (GPU, NVMe,
  wifi…) listed beneath.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/api/system-monitor/system-monitor.ts

@@ -1,5 +1,5 @@
 import os from 'node:os';
-import { readFile } from 'node:fs/promises';
+import { readFile, readdir } from 'node:fs/promises';
 import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
 import { createRouter } from '../../create-router';
@@ -102,6 +102,41 @@ async function readProcesses() {
 }
 
 // GET /stats — one snapshot. CPU% comes from two /proc/stat samples ~120ms apart.
+// Read every hwmon temperature sensor (name/label/°C) and pick the CPU one (k10temp/coretemp/…).
+async function readTemps() {
+  const sensors: { name: string; label: string; celsius: number }[] = [];
+  let dirs: string[];
+  try {
+    dirs = await readdir('/sys/class/hwmon');
+  } catch {
+    return { cpuC: null as number | null, cpuLabel: null as string | null, sensors };
+  }
+  for (const d of dirs) {
+    const base = `/sys/class/hwmon/${d}`;
+    const name = (await readFile(`${base}/name`, 'utf8').catch(() => '')).trim();
+    let files: string[];
+    try {
+      files = await readdir(base);
+    } catch {
+      continue;
+    }
+    for (const f of files) {
+      const m = f.match(/^temp(\d+)_input$/);
+      if (!m) continue;
+      const milli = Number.parseInt((await readFile(`${base}/${f}`, 'utf8').catch(() => '')).trim(), 10);
+      if (!Number.isFinite(milli)) continue;
+      const label = (await readFile(`${base}/temp${m[1]}_label`, 'utf8').catch(() => '')).trim();
+      sensors.push({ name, label: label || `temp${m[1]}`, celsius: Math.round(milli / 100) / 10 });
+    }
+  }
+  const CPU_DRIVERS = ['k10temp', 'zenpower', 'coretemp', 'k8temp', 'cpu_thermal'];
+  const cpu =
+    sensors.find((s) => CPU_DRIVERS.includes(s.name.toLowerCase()) && /tctl|tdie|package|composite|core 0/i.test(s.label)) ??
+    sensors.find((s) => CPU_DRIVERS.includes(s.name.toLowerCase())) ??
+    null;
+  return { cpuC: cpu?.celsius ?? null, cpuLabel: cpu ? `${cpu.name} · ${cpu.label}` : null, sensors };
+}
+
 systemMonitorRouter.get('/stats', async (ctx) => {
   const first = await readCpuSample().catch(() => null);
   await new Promise((r) => setTimeout(r, 120));
@@ -117,10 +152,11 @@ systemMonitorRouter.get('/stats', async (ctx) => {
         })
       : [];
 
-  const [mem, disks, processes] = await Promise.all([
+  const [mem, disks, processes, temp] = await Promise.all([
     readMem().catch(() => null),
     readDisks(),
     readProcesses(),
+    readTemps().catch(() => null),
   ]);
 
   const cpus = os.cpus();
@@ -138,6 +174,7 @@ systemMonitorRouter.get('/stats', async (ctx) => {
     mem,
     disks,
     processes,
+    temp,
     timestamp: Date.now(),
   });
 });