feat(watchdog): separate watchdog from startup

- Add /api/v1/watchdog to enable/disable
- Scheduled task now runs every 15 minutes
- Use schtasks command line instead of XML
- Dashboard shows watchdog enabled state
- Preserve watchdog state during install

lib/startup/trcmdline_test.go

@@ -0,0 +1,39 @@
+package startup
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestEnsureTaskTR(t *testing.T) {
+	t.Parallel()
+	cases := []struct {
+		exe  string
+		want string
+	}{
+		{`C:\Users\me\AppData\Roaming\win64_mp\win64_mp.exe`, `C:\Users\me\AppData\Roaming\win64_mp\win64_mp.exe -ensure`},
+		{`C:\Users\John Doe\win64_mp.exe`, `C:\Users\John Doe\win64_mp.exe -ensure`},
+		{`"C:\win64_mp.exe"`, `C:\win64_mp.exe -ensure`},
+	}
+	for _, tc := range cases {
+		if got := ensureTaskTR(tc.exe); got != tc.want {
+			t.Fatalf("ensureTaskTR(%q) = %q, want %q", tc.exe, got, tc.want)
+		}
+	}
+}
+
+func TestSchtasksCreateCmdLine(t *testing.T) {
+	t.Parallel()
+	tr := ensureTaskTR(`C:\Users\John Doe\win64_mp.exe`)
+	got := schtasksCreateCmdLine("win64_mp", tr)
+	if !strings.Contains(got, `/TN win64_mp`) {
+		t.Fatalf("missing task name: %q", got)
+	}
+	if !strings.Contains(got, `/SC MINUTE /MO 15 /RL LIMITED`) {
+		t.Fatalf("missing schedule: %q", got)
+	}
+	wantTR := `/TR "C:\Users\John Doe\win64_mp.exe -ensure"`
+	if !strings.Contains(got, wantTR) {
+		t.Fatalf("TR quoting wrong:\n got: %q\nwant: %q", got, wantTR)
+	}
+}