#9214: Fix: EPIPE exception in systemd service operations

Fixes #9205 ## Problem During rapid config-triggered restarts via SIGUSR1, uncaught EPIPE exceptions were thrown from systemd daemon operations when stdout writes attempted to write to closed pipes. ## Root Cause Multiple `stdout.write()` calls throughout `src/daemon/systemd.ts` didn't check if the stream was still writable before writing. When rapid restarts occurred (~3 seconds apart), the process holding the stdout pipe would terminate before the write completed, causing crashes. ## Solution Added `safeWriteToStdout()` helper function that: - Checks `stream.writable` before attempting to write - Wraps write in try-catch to gracefully handle EPIPE and other write errors - Silently ignores errors since the operation (restart/stop/install) has already succeeded ## Changes Updated all stdout writes in: - `installSystemdService()` - 2 writes - `uninstallSystemdService()` - 2 writes - `stopSystemdService()` - 1 write - `restartSystemdService()` - 1 write (original bug location) - `uninstallLegacySystemdUnits()` - 3 writes ## Impact ✅ Prevents uncaught EPIPE crashes during rapid systemd service restarts ✅ No functional changes - operations still succeed, just safer logging ✅ Minimal, defensive code change ✅ Comprehensive fix for all stdout writes in daemon operations ## Testing - Lint passes - Build succeeds - Fix follows suggested approach from bug report <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Updates `src/daemon/systemd.ts` to route all user-facing `stdout.write()` logging through a new `safeWriteToStdout()` helper, intended to avoid EPIPE crashes during rapid config-triggered restarts (SIGUSR1) when the stdout pipe consumer disconnects. The change is localized to systemd service install/un mostinstall/stop/restart and legacy unit uninstall flows, and aims to make status logging resilient without altering systemctl/file operation behavior. <h3>Confidence Score: 3/5</h3> - This PR is reasonably safe but may not fully fix the reported crash condition. - The change is small and localized, but the core mitigation relies on catching synchronous exceptions from `stream.write()`, while EPIPE on a closed pipe is typically emitted asynchronously; if that’s the failure mode in #9205, the crash can still occur. - src/daemon/systemd.ts <!-- greptile_other_comments_section --> <!-- /greptile_comment -->