fix(macos): stop podman re-injecting the gateway name into containers

The address-bearing proxy URLs from 892bfc16 were written correctly but
never took effect: podman copies the host's proxy environment into every
container by default, and that copy overrides containers.conf `env`,
restoring the `bot-bottle-gateway` name a nested container cannot
resolve. Verified on the macOS host — containers still reported
`wget: bad address 'bot-bottle-gateway:9099'` with the addresses in
place.

Setting http_proxy=false disables only podman's own passthrough; the
proxy vars still reach containers, by address, from the env list.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/backend/macos_container/nested-containers-init.sh

@@ -136,6 +136,10 @@ path = Path(os.environ["CONTAINERS_CONF"])
 path.write_text("\n".join([
     "[containers]",
     'cgroups="disabled"',
+    # podman copies the host's proxy vars into every container by default,
+    # and that copy *wins* over the env below — putting the unresolvable
+    # gateway name back. Turn it off so the address-bearing URLs stand.
+    "http_proxy=false",
     'hosts_file="/etc/hosts"',
     f'volumes=["{ca}:{ca}:ro"]',
     "env=[",