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>

tests/unit/test_smolmachines_prepare.py

@@ -56,7 +56,6 @@ class TestSmolmachinesResolveEnv(unittest.TestCase):
                     patch("bot_bottle.backend.smolmachines.prepare.smolmachines_bundle_subnet",
                           return_value=("10.99.0.0/24", "10.99.0.1", "10.99.0.2")),
                     patch("bot_bottle.backend.smolmachines.prepare.GitGate") as mock_gg,
-                    patch("bot_bottle.backend.smolmachines.prepare.PipelockProxy") as mock_pl,
                     patch("bot_bottle.backend.smolmachines.prepare.Egress") as mock_eg,
                     patch("bot_bottle.backend.smolmachines.prepare.Supervise"),
                     patch(
@@ -65,7 +64,6 @@ class TestSmolmachinesResolveEnv(unittest.TestCase):
                     patch("bot_bottle.backend.smolmachines.prepare.runtime_for"),
                 ):
                     mock_gg.return_value.prepare.return_value = MagicMock()
-                    mock_pl.return_value.prepare.return_value = MagicMock()
                     mock_eg.return_value.prepare.return_value = MagicMock()
                     def _make_provision(**kwargs):  # type: ignore
                         return AgentProvisionPlan(