fix(sidecars): apply_routes_change targets the bundle + SIGHUP forwarding

Two bugs surfaced when applying an egress route change:

1. egress_apply.py still targeted claude-bottle-egress-<slug> —
   the legacy per-sidecar container that no longer exists (it's
   a docker-network alias on the bundle now). Switched it to
   sidecar_bundle_container_name(slug), matching the chunk-5
   fix already made to pipelock_apply.py.

2. `docker kill --signal HUP <bundle>` lands SIGHUP on the
   supervisor (PID 1 in the bundle), which previously had no
   SIGHUP handler — the signal was ignored. Added
   `_Supervisor.forward_signal(sig, daemon_name)` and a SIGHUP
   handler in main() that forwards to the egress daemon so
   mitmdump's addon reload still works under the bundle.

Tests:
- New _Supervisor.forward_signal cases: forwards to the named
  child (Python subprocess as the SIGHUP target — bash trap +
  stdout=PIPE deferral interferes with the production-style
  test); unknown-daemon name is a no-op.

Stale-reference cleanup (separate issue surfaced while looking
at this):
- claude_bottle/{egress,git_gate,egress_addon,
  egress_addon_core,supervise_server}.py: Dockerfile.egress /
  Dockerfile.git-gate / Dockerfile.supervise references updated
  to Dockerfile.sidecars (the old per-sidecar Dockerfiles were
  deleted in PRD 0024 chunk 5).
- tests/README.md: dropped the entry for
  test_pipelock_sidecar_smoke (deleted in chunk 3) and added
  the new bundle integration tests.
- git_gate.py: stale `DockerGitGate.start via docker cp`
  reference (the method was deleted in chunk 3) rewritten to
  the bind-mount path the renderer uses now.

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

claude_bottle/egress_addon_core.py

@@ -7,8 +7,8 @@ exercise the parse + decision functions without depending on the
 container.
 
 Imports: stdlib + `yaml_subset` (which is itself stdlib-only and
-ships flat into the egress image alongside this file — see
-`Dockerfile.egress`).
+ships flat into the sidecar bundle image alongside this file —
+see `Dockerfile.sidecars`).
 """
 
 from __future__ import annotations
@@ -16,13 +16,11 @@ from __future__ import annotations
 import typing
 from dataclasses import dataclass
 
-# Absolute import — `yaml_subset.py` is copied flat into the egress
-# image's `/app/` next to this file (via `Dockerfile.egress`). The
-# host-side unit tests run with the repo on sys.path, where the
-# bare `yaml_subset` module also resolves because
-# `claude_bottle/yaml_subset.py` shadows it at import time... actually
-# no, on host the module lives under the `claude_bottle` package.
-# The try/except shim picks whichever import works.
+# Absolute import — `yaml_subset.py` is copied flat into the bundle
+# image's `/app/` next to this file (via `Dockerfile.sidecars`).
+# The host-side unit tests run with the repo on sys.path, where the
+# import resolves under the `claude_bottle` package. The try/except
+# shim picks whichever import works.
 try:
     from yaml_subset import YamlSubsetError, parse_yaml_subset  # type: ignore[import-not-found]
 except ImportError:  # pragma: no cover - host-side path