fix: make log viewer optional and document runtime dependencies

bin/netupgrade

@@ -10,11 +10,38 @@ showHelp() {
 }
 
 checkDependencies() {
-	command -v ssh >/dev/null 2>&1 || { echo "Error: ssh is required"; exit 1; }
-	command -v whiptail >/dev/null 2>&1 || { echo "Error: whiptail is required"; exit 1; }
-	command -v nano >/dev/null 2>&1 || { echo "Error: nano is required"; exit 1; }
-	command -v sed >/dev/null 2>&1 || { echo "Error: sed is required"; exit 1; }
-	command -v tee >/dev/null 2>&1 || { echo "Error: tee is required"; exit 1; }
+	local -a REQUIRED_CMDS=(ssh whiptail sed tee rm touch)
+	local -a MISSING_CMDS=()
+	local CMD
+
+	for CMD in "${REQUIRED_CMDS[@]}"; do
+		if ! command -v "${CMD}" >/dev/null 2>&1; then
+			MISSING_CMDS+=("${CMD}")
+		fi
+	done
+
+	if [ ${#MISSING_CMDS[@]} -gt 0 ]; then
+		echo "Error: missing required dependencies: ${MISSING_CMDS[*]}"
+		exit 1
+	fi
+}
+
+resolveLogViewer() {
+	if [ -n "${EDITOR}" ] && command -v "${EDITOR}" >/dev/null 2>&1; then
+		LOGVIEWER="${EDITOR}"
+		return
+	fi
+
+	local -a CANDIDATES=(nano vi less)
+	local CANDIDATE
+	for CANDIDATE in "${CANDIDATES[@]}"; do
+		if command -v "${CANDIDATE}" >/dev/null 2>&1; then
+			LOGVIEWER="${CANDIDATE}"
+			return
+		fi
+	done
+
+	LOGVIEWER=""
 }
 
 pressAnyKey(){
@@ -88,7 +115,11 @@ selectNodes(){
 	sed -i "1s/^/${RESULT//\//\\\/}\n\n\n\n/" "${LOGFILENAME}"
 	sed -i "1s/^/---------\n\n/" "${LOGFILENAME}"
 	sed -i "1s/^/Results :\n/" "${LOGFILENAME}"
-	nano "${LOGFILENAME}"
+	if [ -n "${LOGVIEWER}" ]; then
+		"${LOGVIEWER}" "${LOGFILENAME}"
+	else
+		echo "Warning: no log viewer found, showing log path instead: ${LOGFILENAME}"
+	fi
 	rm -i "${LOGFILENAME}"
 	echo ""
 	echo "Results :"
@@ -235,6 +266,7 @@ declare -i YES=0
 declare -i FULL=0
 declare CONFIGFILENAME="${HOME}/.config/netupgrade/index.cfg"
 declare LOGFILENAME="${HOME}/netupgrade.log"
+declare LOGVIEWER=""
 declare -a NODES=()
 
 while [[ ${#} -gt 0 ]]; do
@@ -247,6 +279,7 @@ while [[ ${#} -gt 0 ]]; do
 done
 
 checkDependencies
+resolveLogViewer
 loadConfig
 selectNodes