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_egress_addon_core.py

@@ -180,7 +180,7 @@ class TestMatchRoute(unittest.TestCase):
     def test_wildcard_hosts_not_supported(self):
         # `*.example.com` is treated as a literal host string by
         # the exact-only matcher. Removed from the design after
-        # the apex/RFC-6125/pipelock-mirror edge cases stacked up.
+        # the apex/RFC-6125 edge cases stacked up.
         routes = (Route(host="*.example.com"),)
         self.assertIsNone(match_route(routes, "foo.example.com"))
         self.assertIsNone(match_route(routes, "example.com"))
@@ -191,10 +191,8 @@ class TestMatchRoute(unittest.TestCase):
 
 class TestDecide(unittest.TestCase):
     def test_no_matching_route_blocks(self):
-        # Defense-in-depth: egress gates the bottle's allowlist
-        # too, not just pipelock. Any host the operator didn't declare
-        # in egress.routes is 403'd at egress before it
-        # ever reaches pipelock.
+        # Egress gates the bottle's allowlist. Any host the operator
+        # didn't declare in egress.routes is 403'd at egress.
         d = decide((), "elsewhere.example", "/anything", {})
         self.assertEqual("block", d.action)
         self.assertIn("allowlist", d.reason)