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/git_gate.py

@@ -147,12 +147,12 @@ def git_gate_known_hosts_line(host: str, port: str, key: str) -> str:
 
 
 def git_gate_render_entrypoint(upstreams: tuple[GitGateUpstream, ...]) -> str:
-    """Posix-sh entrypoint (alpine ash). One `init_repo` call per
-    upstream, then `exec git daemon`. The function reads
-    `/git-gate/creds/<name>-{key,known_hosts}` (laid down by
-    `DockerGitGate.start` via docker cp) and wires them into each
-    bare repo's config; the access-hook + pre-receive hook pick those
-    paths up at fetch / push time."""
+    """Posix-sh entrypoint. One `init_repo` call per upstream, then
+    `exec git daemon`. The function reads
+    `/git-gate/creds/<name>-{key,known_hosts}` (bind-mounted into
+    the bundle by the renderer) and wires them into each bare repo's
+    config; the access-hook + pre-receive hook pick those paths up
+    at fetch / push time."""
     lines = [
         "#!/bin/sh",
         "set -eu",