chore: remove accidentally-committed __pycache__ + gitignore Python caches (#20)

Cleanup of #19's commit, which inadvertently included scripts/__pycache__/
.pyc files generated by running pytest locally during the review-
followup work. The repo's .gitignore had no Python-cache section at
all, so nothing prevented this — adding it now to make the same
mistake structurally impossible.

Files removed from tracking (still ignored locally going forward):
  - scripts/__pycache__/migrate-template.cpython-313.pyc
  - scripts/__pycache__/test_migrate_template.cpython-313-pytest-9.0.3.pyc
  - scripts/__pycache__/test_validate_workspace_template.cpython-313-pytest-9.0.3.pyc
  - scripts/__pycache__/validate-workspace-template.cpython-313.pyc

Gitignore additions cover the standard set:
  __pycache__/, *.pyc, *.pyo, *.pyd, .pytest_cache/, .mypy_cache/,
  .ruff_cache/

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -19,3 +19,12 @@
 # Workspace auth tokens
 .auth-token
 .auth_token
+
+# Python bytecode + caches — never commit. Generated by every test run.
+__pycache__/
+*.pyc
+*.pyo
+*.pyd
+.pytest_cache/
+.mypy_cache/
+.ruff_cache/