Fix import inconsistencies for all commands

The previous fix (PR #40) only addressed the 'up' command by changing
from 'from .up import up' to 'from . import up'. However, all other
commands (down, bootstrap, switch, doctor, init) had the same issue.

In cli.py, all commands are used as modules with .run attribute:
- down.run
- bootstrap.run
- switch.run
- doctor.run
- init.run

But in commands/__init__.py, they were imported as functions instead
of modules, causing AttributeError: 'function' object has no attribute 'run'

This fix applies the same pattern to all commands consistently by
importing them as modules rather than individual functions.

Fixes the error:
AttributeError: 'function' object has no attribute 'run'
at devman/cli.py:25 for 'down' and similar errors for other commands.

Author: claude

src/devman/commands/__init__.py

@@ -1,11 +1,11 @@
 """Command handlers for devman operations."""
 
-from .bootstrap import bootstrap
-from .doctor import doctor
-from .down import down
+from . import bootstrap
+from . import doctor
+from . import down
 from . import index
-from .init import init
-from .switch import switch
+from . import init
+from . import switch
 from . import up
 
 __all__ = [