Feat: crash log (#7)

Merged #6
- crash log (db0e1be9a02f70927124f9f3563df5e9dee3a764)
- perf(watchdog): limit buffer size and optimize crash substring search (https://github.com/versenilvis/IRIS/pull/7/commits/7725434fedf8b32929dc0d71e1256fda13cfdfca)
- refactor(crash): use dynamic buffer for stack trace capture (https://github.com/versenilvis/IRIS/pull/7/commits/07809a4330a1236471e8dae0e83afd4323a4c83a)

root/update.go

@@ -162,6 +162,15 @@ func startBackgroundUpdateCheck() chan updateResult {
 	ch := make(chan updateResult, 1)
 
 	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				WriteCrashLog(r)
+				restoreTerminal()
+				printCrashNotice()
+				startRescueShell()
+				os.Exit(2)
+			}
+		}()
 		defer close(ch)
 
 		// debug override: skip network entirely, resolve immediately