kardianos/service detects Android as a sysv platform and returns Interactive()==false, causing s.Run() to block indefinitely waiting for service control signals that never come. This made both the TUI and server commands hang on Termux -- even Ctrl+Q couldn't exit the TUI because s.Run() never reached rootCmd.Execute().

So, we platform split using Go build tags.

Fixes regression from 73bca40 (service support PR).

• closes attempt to fix the Termux Surge-cli #423

Greptile Summary

This PR fixes a Termux hang by platform-splitting the service backend via Go build tags: on Android, RunService() always calls rootCmd.Execute() directly (bypassing kardianos/service which misdetects Android as sysv and blocks), while non-Android builds retain the existing kardianos/service path. A new native runit/sv backend is added for Termux service management, with correct $PREFIX and SURGE_SV_DIR/SVDIR handling throughout.

Confidence Score: 5/5

Safe to merge — the fix is well-scoped and the only findings are minor style/redundancy issues

All findings are P2. The core fix (build-tag platform split, sv() env filtering, defaultPrefix() usage) is correct. No logic errors or security concerns were found.

cmd/service_ui_termux.go — redundant double stop on uninstall; all new files missing EOF newline

Important Files Changed

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
cmd/service_ui_termux.go:25-31
**`stopTermuxService` called twice on disable**

When the TUI toggle disables the service, `stopTermuxService()` is called explicitly on line 29, and then `uninstallTermuxService()` (line 30) calls it again internally (line 80). The double `sv down surge` is idempotent but redundant — remove the explicit call here since `uninstallTermuxService` already handles it.

```suggestion
	m.ToggleServiceFunc = func(enable bool) error {
		if enable {
			return installTermuxService()
		}
		return uninstallTermuxService()
	}
```

### Issue 2 of 2
cmd/runservice_std.go:23
**Missing newline at end of file**

All nine new files in this PR (`runservice_std.go`, `runservice_termux.go`, `service_android_test.go`, `service_kardianos.go`, `service_kardianos_test.go`, `service_termux.go`, `service_termux_test.go`, `service_ui_std.go`, `service_ui_termux.go`) are missing a trailing newline. POSIX requires text files to end with a newline and many Go tooling checks (e.g., `gofmt`) flag this as a diff noise issue.

_{Reviews (7): Last reviewed commit: "fix: native Termux runit service backend" | Re-trigger Greptile}