fix: add pressure stubs for Windows/FreeBSD (release build fix)

GoReleaser cross-compilation failed because availableMemoryGB and
loadAverage1Sysctl were only defined for darwin and linux.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: steveyegge

internal/daemon/pressure_other.go

@@ -0,0 +1,13 @@
+//go:build !darwin && !linux && !windows
+
+package daemon
+
+// loadAverage1Sysctl is a no-op on unsupported platforms.
+func loadAverage1Sysctl() float64 {
+	return 0
+}
+
+// availableMemoryGB is a no-op on unsupported platforms.
+func availableMemoryGB() float64 {
+	return 0
+}

internal/daemon/pressure_windows.go

@@ -0,0 +1,11 @@
+package daemon
+
+// loadAverage1Sysctl is a no-op on Windows — load average is not a standard metric.
+func loadAverage1Sysctl() float64 {
+	return 0
+}
+
+// availableMemoryGB is a no-op on Windows — pressure checks are not supported.
+func availableMemoryGB() float64 {
+	return 0
+}