Ignore and clean up stray -.o file from crc32cer compilation

During cmake compilation of the crc32cer dependency (used by Kafka
integration), a stray object file named "-.o" is occasionally created
in the repository root. This appears to happen during cmake's compiler
detection/test phase.

This commit:
- Adds -.o to .gitignore to prevent it from appearing in git status
- Updates bin/bootstrap to automatically remove the file after
  dependency compilation

The dash prefix makes this file particularly annoying since it's
interpreted as a command-line option by most tools.

Author: stuartc

.gitignore

@@ -22,6 +22,9 @@ erl_crash.dump
 # Ignore package tarball (built via "mix hex.build").
 lightning-*.tar
 
+# Ignore stray cmake object file from crc32cer compilation
+-.o
+
 # Ignore adaptor registry cache
 adaptor_registry_cache.json
 

bin/bootstrap

@@ -255,6 +255,13 @@ main() {
 
   mix deps.compile
 
+  # Clean up stray object file created by crc32cer cmake compilation
+  # This file sometimes escapes the build directory during cmake's compiler tests
+  if [[ -f "-.o" ]]; then
+    echo "🧹 Cleaning up stray cmake artifact (-.o)"
+    rm -f ./-.o
+  fi
+
   # If you have already compiled Rambo explicitly via `mix compile.rambo`, and you
   # are still seeing the following error:
   #