Add pytest and Python linting (ruff) to CI (#1637)

* feat: add GitHub Actions workflow for testing and linting Python code

* fix: resolve ruff lint errors in specify_cli

- Remove extraneous f-string prefixes (F541)
- Split multi-statement lines (E701, E702)
- Remove unused variable assignments (F841)
- Remove ruff format check from CI workflow (format-only PR to follow)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: strip ANSI codes in ai-skills help text test

The Rich/Typer CLI injects ANSI escape codes into option names in
--help output, causing plain string matching to fail.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/test_ai_skills.py

@@ -10,6 +10,7 @@ Tests cover:
 - CLI validation: --ai-skills requires --ai
 """
 
+import re
 import pytest
 import tempfile
 import shutil
@@ -626,5 +627,6 @@ class TestCliValidation:
         runner = CliRunner()
         result = runner.invoke(app, ["init", "--help"])
 
-        assert "--ai-skills" in result.output
-        assert "agent skills" in result.output.lower()
+        plain = re.sub(r'\x1b\[[0-9;]*m', '', result.output)
+        assert "--ai-skills" in plain
+        assert "agent skills" in plain.lower()