Restructure nav to Load/Burn/Benchmark; fix SAA acpidump dependency

- Nav steps 3-5: Load (validate), Burn (burn-in), Benchmark (speed+endurance merged)
- /load now renders validate mode; /burn renders burn-in; /benchmark replaces /speed+/endurance
- Legacy redirects updated: /validate→/load, /burn-in→/burn, /speed+/endurance→/benchmark
- Add acpica_bin/acpidump from SAA 1.5.0 package; required by saa GetDmiInfo (ExitCode 8)
- build.sh copies acpica_bin/acpidump to /usr/local/bin/acpica_bin/ alongside saa

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

audit/internal/webui/layout.go

@@ -106,8 +106,8 @@ func layoutNav(active string, buildLabel string) string {
 		{id: "audit", label: "1. Audit", href: "/audit"},
 		{id: "check", label: "2. Check", href: "/check"},
 		{id: "load", label: "3. Load", href: "/load"},
-		{id: "speed", label: "4. Speed", href: "/speed"},
-		{id: "endurance", label: "5. Endurance", href: "/endurance"},
+		{id: "burn", label: "4. Burn", href: "/burn"},
+		{id: "benchmark", label: "5. Benchmark", href: "/benchmark"},
 		{sep: true},
 		{id: "tasks", label: "Tasks", href: "/tasks"},
 		{id: "tools", label: "Tools", href: "/tools"},