fix: convert tarball path to absolute and run on PRs

- Convert PACKAGE_TARBALL to absolute path before cd to avoid path resolution issues
- Add pull_request trigger to smoke-test workflow so it runs on PRs

Addresses Codex feedback about tarball path being relative after cd.

_Generated with `mux`_

Author: ibetitsmike

.github/workflows/smoke-test.yml

@@ -1,6 +1,8 @@
 name: Smoke Test
 
 on:
+  pull_request:
+    branches: ["**"]
   push:
     branches:
       - main

scripts/smoke-test.sh

@@ -71,6 +71,9 @@ if [[ ! -f "$PACKAGE_TARBALL" ]]; then
   exit 1
 fi
 
+# Convert to absolute path before changing directories
+PACKAGE_TARBALL=$(realpath "$PACKAGE_TARBALL")
+
 log_info "Starting smoke test for package: $PACKAGE_TARBALL"
 
 # Create temporary test directory