fix(git): handle exit code 1 from git add --dry-run

Git returns exit code 1 (not 128) when some files are ignored.
- Accept both returncode 1 and 128 for ignore detection
- Parse ignored paths per-batch to avoid cross-batch contamination
- Log ignored file count after filtering

Testing showed: exit code 1 = some ignored, 0 = none ignored

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/auto_commit_service/git/operations.py

@@ -203,9 +203,11 @@ async def git_check_ignored(repo_path: Path, files: list[str]) -> list[str]:
             if returncode == 0:
                 # All files in batch are safe
                 safe_files.extend(batch)
-            elif returncode == 128 and "ignored" in stderr.lower():
+            elif (returncode == 1 or returncode == 128) and "ignored" in stderr.lower():
                 # Some files are ignored - parse error message to find which ones
                 # Git error format: "The following paths are ignored by one of your .gitignore files:\npath1\npath2"
+                # Exit code 1 = some files ignored, 128 = all files ignored
+                batch_ignored = []
                 lines = stderr.split("\n")
                 for i, line in enumerate(lines):
                     if "following paths are ignored" in line.lower():
@@ -215,10 +217,11 @@ async def git_check_ignored(repo_path: Path, files: list[str]) -> list[str]:
                                 break
                             ignored_path = ignored_line.strip()
                             if ignored_path:
+                                batch_ignored.append(ignored_path)
                                 ignored_files.append(ignored_path)
 
                 # Files not in ignored list are safe
-                safe_files.extend([f for f in batch if f not in ignored_files and not any(f.startswith(ig + "/") for ig in ignored_files)])
+                safe_files.extend([f for f in batch if f not in batch_ignored and not any(f.startswith(ig + "/") for ig in batch_ignored)])
             else:
                 # Unknown error - be conservative and include all files
                 logger.warning(f"git add --dry-run returned {returncode}: {stderr}, including all files from batch")