[WIP] Lock file must be deleted when user trigger a sigint through ctrl-c (#137)

* Initial plan

* Fix lock file cleanup on SIGINT and improve stale lock handling

Co-authored-by: paolomainardi <8747+paolomainardi@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: paolomainardi <8747+paolomainardi@users.noreply.github.com>

Author: Copilot

bin/sparkdock.macos

@@ -30,8 +30,8 @@ cleanup_lock() {
     fi
 }
 
-# Set up trap at the start to catch all exits
-trap cleanup_lock EXIT
+# Set up trap at the start to catch all exits and interruptions
+trap cleanup_lock EXIT INT TERM
 
 check_for_updates() {
     cd "$SPARKDOCK_ROOT"
@@ -66,9 +66,8 @@ check_for_updates() {
             exit 1
         else
             print_warning "Lock file exists but the process (PID: $pid) is no longer running."
-            print_warning "If you believe this is a stale lock file, you can remove it manually by running:"
-            print_warning "  rm -f $LOCK_FILE"
-            exit 1
+            print_warning "Removing stale lock file and continuing..."
+            rm -f "$LOCK_FILE"
         fi
     fi
     echo $$ > "$LOCK_FILE"