revert(egress-proxy): drop Role + agent provisioner (keep git-push block)

Partial revert of fa06a3a. The role + agent-side provisioner felt
overengineered: anthropic-base-url + npm-registry's only realistic
host values match the tool defaults, so the role tags drove no-op
dotfile writes most of the time. If non-default npm registry / tea
config is needed in a future bottle, we can ship it through a more
direct mechanism then.

What stays from fa06a3a:
  - Universal HTTPS git-push block in the egress-proxy addon
    (`is_git_push_request` in egress_proxy_addon_core, called from
    the request hook before route matching; 403s git-receive-pack
    regardless of route). This is the security backstop so git-gate
    remains the only outbound write path; PR #29 keeps it.

What gets reverted:
  - `Role` field on EgressProxyRoute (manifest + runtime).
  - `EGRESS_PROXY_ROLES` + `EGRESS_PROXY_SINGLETON_ROLES` constants
    and singleton-role validation.
  - `backend/docker/provision/egress_proxy.py` (npmrc + tea config).
  - `provision_egress_proxy` slot in `BottleBackend.provision`.
  - `prepare.py`'s role-based ANTHROPIC_BASE_URL detection (back to
    the token_ref="CLAUDE_CODE_OAUTH_TOKEN" auto-detect).
  - Manifest + provisioner tests for the above.

355 unit + 24 integration tests pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

claude_bottle/backend/docker/backend.py

@@ -27,7 +27,6 @@ from .egress_proxy import DockerEgressProxy
 from .git_gate import DockerGitGate
 from .pipelock import DockerPipelockProxy
 from .provision import ca as _ca
-from .provision import egress_proxy as _egress_proxy_prov
 from .provision import git as _git
 from .provision import prompt as _prompt
 from .provision import skills as _skills
@@ -81,9 +80,6 @@ class DockerBottleBackend(BottleBackend["DockerBottlePlan", "DockerBottleCleanup
     def provision_git(self, plan: DockerBottlePlan, target: str) -> None:
         _git.provision_git(plan, target)
 
-    def provision_egress_proxy(self, plan: DockerBottlePlan, target: str) -> None:
-        _egress_proxy_prov.provision_egress_proxy(plan, target)
-
     def provision_supervise(self, plan: DockerBottlePlan, target: str) -> None:
         _supervise_prov.provision_supervise(plan, target)