chore(gitignore): add pytest-cov, htmlcov, and vim swap patterns

Round out the gitignore with a few additional dev-artifact patterns
not previously covered:

- coverage.xml + htmlcov/ -- pytest-cov XML/HTML report outputs
- .pytest_cache/ -- pytest's cache; previously self-ignored via its
  own .gitignore but more discoverable at the repo root
- *.swp / *.swo -- vim swap files

No project-specific additions; just generic dev-artifact coverage.

Signed-off-by: lelia <2418071+lelia@users.noreply.github.com>

Author: lelia

.gitignore

@@ -2,6 +2,9 @@
 *.pyc
 __pycache__/
 .coverage
+coverage.xml
+htmlcov/
+.pytest_cache/
 
 # --- Virtual environments ---
 venv/
@@ -20,6 +23,8 @@ dist/
 
 # --- Editor / IDE ---
 .idea/
+*.swp
+*.swo
 
 # --- OS ---
 .DS_Store