refactor(cli): group subcommand handlers under cli/commands/

Move the eleven per-command modules (backend, cleanup, commit, edit,
info, init, list, login, resume, start, supervise) into a new
bot_bottle/cli/commands/ package, leaving the dispatcher (__init__),
entrypoint (__main__), and shared helpers (_common, tui) at the cli
root. Makes the command surface obvious at a glance and separates
handlers from the plumbing that registers them.

Updated the dispatcher's COMMANDS imports to .commands.*, bumped the
moved files' relative-import depths (.._common, .. import tui, sibling
.start unchanged), and repointed test references to
bot_bottle.cli.commands.*. Full unit suite green (2243); CLI dispatch
verified via `python -m bot_bottle.cli --help`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/unit/test_cli_start_settle.py

@@ -10,7 +10,7 @@ from pathlib import Path
 
 from tests.unit import use_bottle_root
 from bot_bottle import bottle_state
-from bot_bottle.cli import start as start_mod
+from bot_bottle.cli.commands import start as start_mod
 
 
 class _FakeHomeMixin: