fix(cred_proxy): close git-push bypass + route through pipelock (PRD 0010)

Three coupled fixes that close a documented bypass of git-gate's
gitleaks pre-receive hook:

1. cred-proxy refuses git smart-HTTP push at runtime. Any path
   ending in /git-receive-pack or /info/refs?service=git-receive-pack
   returns 403 with a pointer at the bottle.git SSH path. Fetch
   (upload-pack) is still allowed — the bypass we're closing is
   push, where gitleaks is the load-bearing scanner. Hard guarantee.

2. The provisioner suppresses the cred-proxy `~/.gitconfig` insteadOf
   rewrite for any host already declared in bottle.git. git-gate is
   the canonical git path there; we don't write a competing rule
   that would let `git clone https://<host>/...` succeed in ways
   that confuse on push. Defense in depth — (1) is the hard guarantee.

3. cred-proxy routes its outbound HTTPS through pipelock. The
   sidecar's environ now sets HTTPS_PROXY=<pipelock-url>, and the
   image's entrypoint runs `update-ca-certificates` over the
   per-bottle pipelock CA (docker cp'd into
   /usr/local/share/ca-certificates/pipelock.crt before start) so
   the proxy's HTTPS client trusts pipelock's bumped certs.

   Consequence: pipelock's allowlist + body scanner now sit in the
   cred-proxy egress path the same way they sit in front of direct
   agent traffic. The cred-proxy upstream hosts (api.github.com,
   github.com, gitea hosts, registry.npmjs.org) come OFF
   pipelock's passthrough_domains. Only api.anthropic.com remains
   on passthrough (LLM body content legitimately trips DLP).

PRD 0010 updated to reflect all three. Tests adjusted: the
"cred-proxy hosts go on passthrough" assertion in
test_pipelock_allowlist flips to "they don't", a new
TestIsGitPushRequest exercises the smart-HTTP refusal predicate,
and the gitconfig renderer tests cover the per-host suppression
matrix.

tests/unit/test_docker_cred_proxy.py

@@ -4,6 +4,7 @@ The full docker lifecycle is exercised by integration tests; here we
 cover the pure helpers and the validation checks `.start` runs
 before touching docker."""
 
+import tempfile
 import unittest
 from pathlib import Path
 
@@ -26,6 +27,8 @@ def _empty_plan(**overrides):
         "token_env_map": {},
         "internal_network": "",
         "egress_network": "",
+        "pipelock_ca_host_path": Path(),
+        "pipelock_proxy_url": "",
     }
     base.update(overrides)
     return CredProxyPlan(**base)
@@ -77,6 +80,26 @@ class TestStartGuards(unittest.TestCase):
                 routes_path=Path("/tmp/cred-proxy-test-does-not-exist.json"),
             ))
 
+    def test_pipelock_url_without_ca_dies(self):
+        # URL set + CA path empty/missing is a wiring bug: either both
+        # populated (production) or both empty (test escape hatch).
+        upstream = CredProxyUpstream(
+            kind="anthropic", path="/anthropic/",
+            upstream="https://api.anthropic.com",
+            auth_scheme="Bearer", token_env="CRED_PROXY_TOKEN_0",
+            token_ref="T",
+        )
+        with tempfile.NamedTemporaryFile() as routes:
+            with self.assertRaises(Die):
+                self.proxy.start(_empty_plan(
+                    upstreams=(upstream,),
+                    internal_network="net-x",
+                    egress_network="egress-x",
+                    routes_path=Path(routes.name),
+                    pipelock_proxy_url="http://pipelock:8888",
+                    pipelock_ca_host_path=Path("/tmp/cred-proxy-no-ca.pem"),
+                ))
+
 
 if __name__ == "__main__":
     unittest.main()