refactor: convert project from bash to Python

Replaces cli.sh + lib/*.sh with a claude_bottle/ Python package and a
cli.py entry point. No external dependencies — uses only Python's
stdlib (json, subprocess, getpass, tempfile, argparse, re, etc.).

- claude_bottle/{log,docker,manifest,env_resolve,network,pipelock,
  skills,ssh,cli}.py mirror the previous lib/*.sh modules.
- Tests converted to unittest under tests/test_*.py with a stdlib
  runner at tests/run_tests.py (unit | integration | path).
- .githooks/commit-msg ported to Python; same Conventional Commits rules.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/_docker.py

@@ -0,0 +1,24 @@
+"""Docker availability check used by integration tests."""
+
+from __future__ import annotations
+
+import shutil
+import subprocess
+import unittest
+
+
+def docker_available() -> bool:
+    if shutil.which("docker") is None:
+        return False
+    return (
+        subprocess.run(
+            ["docker", "info"],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        ).returncode
+        == 0
+    )
+
+
+def skip_unless_docker(reason: str = "docker unreachable"):
+    return unittest.skipUnless(docker_available(), reason)