chore: remove all pipelock references from tests, docs, and non-pipelock source

- Strip pipelock from all unit and integration test fixtures:
  proxy_plan fields removed from DockerBottlePlan/SmolmachinesBottlePlan
  constructors; pipelock-specific test classes deleted or renamed
- Update test_sidecar_init: remove test_pipelock_loses_egress_tokens,
  rename "pipelock" daemon fixtures to "git-gate" throughout
- Remove test_pipelock_binary_present_and_versioned from integration test
- Remove test_pipelock_answers_on_bundle_ip from smolmachines launch test
- Update _SANDBOX_BLOCK_MARKERS: remove "pipelock" marker (egress blocks)
- Dockerfile.sidecars: remove pipelock build stage and COPY; update layout
  comments and port table
- egress_entrypoint.sh: update comments now that egress is sole proxy
- Clean up pipelock references in comments/docstrings across backend,
  network, manifest, supervise, git_gate, yaml_subset, agent_provider,
  sidecar_bundle, sidecar_init, egress_addon_core modules

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile.claude

@@ -21,7 +21,7 @@ FROM node:22-slim
 # runs as root and rejects non-root connections, so socat sits between
 # node and the agent socket. curl is here so any HTTPS_PROXY-aware
 # tool (curl itself, plus anything that shells out to it) works
-# against pipelock's bumped TLS without the agent needing local DNS.
+# against egress's bumped TLS without the agent needing local DNS.
 RUN apt-get update \
   && apt-get install -y --no-install-recommends git ca-certificates openssh-client socat curl dnsutils python3 python3-pip python3-venv \
   && rm -rf /var/lib/apt/lists/*