Initial commit: full Phases 1-6 implementation

Post-repair hardware validation pipeline for Proxmox cluster hosts.
Go orchestrator + in-image agent + mkosi live image + bundled dnsmasq
PXE + SQLite + HTMX/SSE UI + notify registry + janitor + full docs.

agent/probes/thermal.go

@@ -0,0 +1,67 @@
+package probes
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// ThermalSample is one reading from /sys/class/hwmon. Kind is "temp",
+// Key is the label (or chip-relative name) and Value is degrees C.
+type ThermalSample struct {
+	Kind  string
+	Key   string
+	Value float64
+	Unit  string
+}
+
+// Thermals walks /sys/class/hwmon looking for temp*_input files. The
+// kernel reports millidegrees C; we divide by 1000. Labels come from
+// temp*_label (preferred) or a chip-relative fallback.
+//
+// This is also used by the thermal sidecar; it re-reads on each tick
+// rather than holding open handles so hot-plugged sensors (e.g. a PCIe
+// card enumerating late) get picked up.
+func Thermals() []ThermalSample {
+	root := "/sys/class/hwmon"
+	chips, err := os.ReadDir(root)
+	if err != nil {
+		return nil
+	}
+	var out []ThermalSample
+	for _, c := range chips {
+		base := filepath.Join(root, c.Name())
+		chipName := strings.TrimSpace(readFileStr(filepath.Join(base, "name")))
+		files, err := os.ReadDir(base)
+		if err != nil {
+			continue
+		}
+		for _, f := range files {
+			name := f.Name()
+			if !strings.HasPrefix(name, "temp") || !strings.HasSuffix(name, "_input") {
+				continue
+			}
+			idx := strings.TrimSuffix(strings.TrimPrefix(name, "temp"), "_input")
+			label := strings.TrimSpace(readFileStr(filepath.Join(base, "temp"+idx+"_label")))
+			if label == "" {
+				label = chipName + "/temp" + idx
+			}
+			raw := strings.TrimSpace(readFileStr(filepath.Join(base, name)))
+			milli, err := strconv.Atoi(raw)
+			if err != nil {
+				continue
+			}
+			out = append(out, ThermalSample{Kind: "temp", Key: label, Value: float64(milli) / 1000, Unit: "C"})
+		}
+	}
+	return out
+}
+
+func readFileStr(p string) string {
+	b, err := os.ReadFile(p)
+	if err != nil {
+		return ""
+	}
+	return string(b)
+}