refactor(platform): rename claude_bottle/bottles -> claude_bottle/platform

'bottles' was the package name when it held a single Bottle Protocol;
since we added BottlePlatform / BottlePlan / BottleCleanupPlan and
made it the home of platform dispatch, 'platform' describes the
package better. The 'bottle' concept (and the manifest field) stays.

CLI imports update from ..bottles to ..platform; internal relative
imports inside the package survive the rename unchanged. Git
detected all 7 file renames.

claude_bottle/cli/cleanup.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 
 import sys
 
-from ..bottles import get_bottle_platform
+from ..platform import get_bottle_platform
 from ..log import info
 from ._common import read_tty_line
 

claude_bottle/cli/list.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 
 import argparse
 
-from ..bottles import get_bottle_platform
+from ..platform import get_bottle_platform
 from ..manifest import Manifest
 from ._common import PROG, USER_CWD
 

claude_bottle/cli/start.py

@@ -11,7 +11,7 @@ import sys
 import tempfile
 from pathlib import Path
 
-from ..bottles import BottleSpec, get_bottle_platform
+from ..platform import BottleSpec, get_bottle_platform
 from ..log import info
 from ..manifest import Manifest
 from ._common import PROG, USER_CWD, read_tty_line

claude_bottle/platform/docker/__init__.py

@@ -9,7 +9,7 @@ The bulk of the implementation lives in sibling modules:
   - platform:             DockerBottlePlatform
 
 This file only re-exports the public names so
-`from claude_bottle.bottles.docker import DockerBottlePlatform` keeps
+`from claude_bottle.platform.docker import DockerBottlePlatform` keeps
 working.
 """