fix: use unique commit instead of deterministic Owner variant for wrong-commit PR tests

PRWrongCommitPushedBeforeEvent and test_push_to_nostr_ref_with_wrong_commit_after_event_received_rejected
were calling create_deterministic_commit_with_variant(CommitVariant::Owner) on a clone that already
had test.txt with 'Initial commit\n' content from OwnerStateDataPushed. Writing identical content
staged nothing so git commit failed silently.

Now that ValidRepoServed always depends on OwnerStateDataPushed (git data pushed), the clone is
never empty - use create_commit (unique file) instead since the wrong commit only needs to differ
from PR_TEST_COMMIT_HASH, not be deterministic.

grasp-audit/src/fixtures.rs

@@ -1579,10 +1579,14 @@ impl<'a> TestContext<'a> {
             let _ = fs::remove_dir_all(path);
         };
 
-        // Create a WRONG commit (Owner variant, not PRTestCommit)
-        // This commit hash will NOT match what's in the PR event's `c` tag
+        // Create a WRONG commit using a unique file (not PRTestCommit)
+        // We use create_commit (non-deterministic) so it always succeeds even if the
+        // repo already has a commit (e.g. from OwnerStateDataPushed) with the same
+        // deterministic content. The only requirement is that the hash differs from
+        // PR_TEST_COMMIT_HASH, which is guaranteed since PR_TEST_COMMIT_HASH is a
+        // deterministic root-commit with specific content and dates.
         let wrong_commit_hash =
-            match create_deterministic_commit_with_variant(&clone_path, CommitVariant::Owner) {
+            match create_commit(&clone_path, "wrong commit - not the PR test commit") {
                 Ok(h) => h,
                 Err(e) => {
                     cleanup(&clone_path);

grasp-audit/src/specs/grasp01/push_authorization.rs

@@ -1231,9 +1231,9 @@ impl PushAuthorizationTests {
             }
         };
 
-        // Create a wrong commit (Owner variant, not PRTestCommit)
-        if let Err(e) = create_deterministic_commit_with_variant(&clone_path, CommitVariant::Owner)
-        {
+        // Create a wrong commit (unique, not PRTestCommit) - use create_commit so it always
+        // succeeds even when the clone already has the Owner deterministic content on disk.
+        if let Err(e) = create_commit(&clone_path, "wrong commit - not the PR test commit") {
             let _ = fs::remove_dir_all(&clone_path);
             return TestResult::new(test_name, SpecRef::GitAcceptRefsNostrEventId, desc).fail(&e);
         }