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/platform/docker/bottle_cleanup_plan.py

@@ -0,0 +1,36 @@
+"""DockerBottleCleanupPlan — concrete subclass of BottleCleanupPlan.
+
+Holds the tuples of container and network names that
+DockerBottlePlatform.cleanup will remove. The y/N preflight reads
+these via `print`; the CLI short-circuits via `empty`.
+"""
+
+from __future__ import annotations
+
+import sys
+from dataclasses import dataclass
+
+from ...log import info
+from .. import BottleCleanupPlan
+
+
+@dataclass(frozen=True)
+class DockerBottleCleanupPlan(BottleCleanupPlan):
+    """Resources DockerBottlePlatform.cleanup will remove. Produced by
+    `prepare_cleanup` from a snapshot of `docker ps -a` + `docker
+    network ls`; sorted so the y/N output is stable."""
+
+    containers: tuple[str, ...]
+    networks: tuple[str, ...]
+
+    @property
+    def empty(self) -> bool:
+        return not self.containers and not self.networks
+
+    def print(self) -> None:
+        print(file=sys.stderr)
+        for name in self.containers:
+            info(f"container: {name}")
+        for name in self.networks:
+            info(f"network:   {name}")
+        print(file=sys.stderr)