Add --raw flag to csv command to skip aggregation

- Add `to_csv_entries()` to output.py: converts raw rows to write_csv
  entries one-for-one, without merging by (project, description)
- Add `--raw` flag to the csv subparser; _cmd_csv branches on it
- Add TestToCsvEntries with 6 tests
- Update README with --raw usage example
- Add .coverage and htmlcov/ to .gitignore

src/timesheets/output.py

@@ -11,6 +11,26 @@ from .projects import resolve_project_task
 from .utils import decimal_to_hhmm
 
 
+def to_csv_entries(rows: list[dict]) -> list[dict]:
+    """Convert raw parsed rows to write_csv-compatible entries without aggregating.
+
+    Each row becomes its own entry. Open entries (duration_hours is None) are
+    skipped. Rows are not combined, even if they share the same project and
+    description.
+    """
+    from .parser import build_description
+
+    return [
+        {
+            "project": row["project"].strip(),
+            "description": build_description(row["story"], row["note"]),
+            "quantity": row["duration_hours"],
+        }
+        for row in rows
+        if row["duration_hours"] is not None
+    ]
+
+
 def write_csv(
     aggregated: list[dict],
     output: IO[str],