refactor: rename egress-proxy → egress everywhere

The manifest key is `egress:` now; finish the rename so the rest of
the codebase matches. Files (Dockerfile.egress, claude_bottle/egress.py
etc.), classes (Egress, EgressConfig, EgressRoute, EgressPlan,
DockerEgress), constants (EGRESS_HOSTNAME, EGRESS_ROUTES, ...),
container name prefix (claude-bottle-egress-*), docker network alias
(egress), the introspection host (_egress.local), the MCP tool IDs
(egress-block, list-egress-routes), and the preflight label all drop
the `-proxy` suffix.

claude_bottle/backend/docker/network.py

@@ -1,4 +1,4 @@
-"""Docker network plumbing for the per-agent egress-proxy topology.
+"""Docker network plumbing for the per-agent egress topology.
 
 The agent container sits on a Docker `--internal` network (no default
 gateway). Pipelock straddles that network and a per-agent user-defined