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>

claude_bottle/log.py

@@ -0,0 +1,23 @@
+"""Tiny logging wrappers. All output goes to stderr."""
+
+from __future__ import annotations
+
+import sys
+
+
+def info(msg: str) -> None:
+    print(f"claude-bottle: {msg}", file=sys.stderr)
+
+
+def warn(msg: str) -> None:
+    print(f"claude-bottle: warning: {msg}", file=sys.stderr)
+
+
+class Die(SystemExit):
+    """Raised by die() so callers (and tests) can distinguish a deliberate
+    fatal exit from an unrelated SystemExit."""
+
+
+def die(msg: str) -> "Die":
+    print(f"claude-bottle: error: {msg}", file=sys.stderr)
+    raise Die(1)