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>

bot_bottle/agent_provider.py

@@ -84,9 +84,9 @@ class AgentProvisionPlan:
     return the same shape without adding backend-plan fields.
 
     `egress_routes` are provider-declared EgressRoutes that backends
-    pass to `Egress.prepare` and `PipelockProxy.prepare`. This keeps
-    provider logic out of the egress and pipelock modules — they merge
-    provider routes generically without knowing the provider type.
+    pass to `Egress.prepare`. This keeps provider logic out of the
+    egress module — it merges provider routes generically without
+    knowing the provider type.
 
     `hidden_env_names` is the set of env var names the provider injected
     as non-secret placeholders. `print_util.visible_agent_env_names` uses