refactor(sidecars): instantiate sidecar ABCs directly from any backend

The four sidecar prepare-time helpers (PipelockProxy, Egress, GitGate,
Supervise) had docker-flavored subclasses that existed only as
instantiation shims for ABCs that already had no abstract methods.
PipelockProxy.prepare() reached for class-level CA path constants
that were only defined on the docker subclass — so smolmachines had
to import DockerPipelockProxy to render pipelock yaml, reaching
across the backend boundary for what's actually a platform-neutral
operation.

This moves the universal in-container CA paths
(PIPELOCK_CA_CERT_IN_CONTAINER / PIPELOCK_CA_KEY_IN_CONTAINER) to
claude_bottle/pipelock.py, drops the class-attr indirection on the
ABC, and deletes the four empty docker subclasses. Both backends
now instantiate the ABCs directly; the docker-side modules keep
the docker-flavored helpers (image pin, container naming, host CA
mint) and re-export the moved pipelock constants for compat.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

claude_bottle/backend/docker/pipelock.py

@@ -1,14 +1,12 @@
-"""DockerPipelockProxy — the Docker-specific implementation of the
-sidecar's `.prepare()` step + in-container CA path constants.
-Inherits the platform-agnostic YAML-config generation from
-PipelockProxy.
+"""Docker-side pipelock helpers: image pin, container naming, and
+the one-shot `pipelock tls init` host-side CA mint. The
+prepare-time YAML rendering itself lives on the platform-neutral
+`PipelockProxy` ABC — backends instantiate it directly.
 
 The per-container `.start()` / `.stop()` lifecycle was deleted in
-PRD 0024 chunk 3 — compose-up owns the container lifecycle (PRD
+PRD 0024 chunk 3; compose-up owns the container lifecycle (PRD
 0018) and the bundle path (PRD 0024) collapses pipelock + egress
-+ git-gate + supervise into one container. What remains here is
-the prepare-time YAML rendering + the CA path constants the
-compose renderer reads."""
++ git-gate + supervise into one container."""
 
 from __future__ import annotations
 
@@ -17,7 +15,13 @@ import subprocess
 from pathlib import Path
 
 from ...log import die
-from ...pipelock import PipelockProxy
+# Re-exported for the compose renderer + smolmachines launch step
+# (they used to import these from this module before they moved to
+# the platform-neutral pipelock module).
+from ...pipelock import (  # noqa: F401
+    PIPELOCK_CA_CERT_IN_CONTAINER,
+    PIPELOCK_CA_KEY_IN_CONTAINER,
+)
 
 
 # Pipelock image, pinned by digest. The digest is the multi-arch image
@@ -30,12 +34,6 @@ PIPELOCK_IMAGE = os.environ.get(
 # Listening port for pipelock's forward proxy.
 PIPELOCK_PORT = os.environ.get("CLAUDE_BOTTLE_PIPELOCK_PORT", "8888")
 
-# In-container paths where the per-bottle CA cert + key land via
-# the compose renderer's bind-mounts. Pipelock's rendered YAML
-# references these paths under `tls_interception`.
-PIPELOCK_CA_CERT_IN_CONTAINER = "/etc/pipelock-ca.pem"
-PIPELOCK_CA_KEY_IN_CONTAINER = "/etc/pipelock-ca-key.pem"
-
 
 def pipelock_container_name(slug: str) -> str:
     return f"claude-bottle-pipelock-{slug}"
@@ -82,13 +80,3 @@ def pipelock_tls_init(stage_dir: Path) -> tuple[Path, Path]:
     key.chmod(0o600)
     cert.chmod(0o644)
     return (cert, key)
-
-
-class DockerPipelockProxy(PipelockProxy):
-    """Docker-flavored PipelockProxy: inherits `.prepare()` from the
-    base, exposes the in-container CA paths the renderer reads.
-    Container lifecycle is owned by compose."""
-
-    CA_CERT_IN_CONTAINER = PIPELOCK_CA_CERT_IN_CONTAINER
-    CA_KEY_IN_CONTAINER = PIPELOCK_CA_KEY_IN_CONTAINER
-