refactor(de-sidecar): purge the "sidecar" name from live code, tests, and current docs

Completes the de-sidecar cleanup: no live code, test, current doc,
script, or nix file mentions or is named "sidecar" any more. Only the
dated PRD/research docs keep the term as historical record (agreed on
the #385 thread).

- Rename `sidecar_init.py`→`gateway_init.py` was done earlier; this pass
  sweeps the remaining descriptive uses: the egress / git-gate / supervise
  components are the gateway's *daemons*, the shared container is the
  *gateway*, the old per-bottle container was the *companion container*.
- Rename `tests/integration/test_sidecar_bundle_image.py`→`test_gateway_image.py`
  and its class; update `docs/ci.md` + `tests/README.md` for the renamed/
  removed integration tests.
- `SIDECAR_PORTS` shell var in `scripts/firecracker-netpool.sh`→`GATEWAY_PORTS`.

Full unit suite green (bar the pre-existing `/bin/sleep`-missing env
errors in test_gateway_init); docker integration — gateway singleton,
broker, real two-bottle multitenant isolation, and the gateway-image
build — all pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

tests/integration/test_gateway_image.py

@@ -0,0 +1,117 @@
+"""Integration: PRD 0024 chunk 1 — the gateway image builds
+and the daemon binaries are present + executable inside it.
+
+This test does NOT exercise the daemons running against real
+config (routes.yaml, etc) — that lands in chunk 2 when the
+renderer wires the bundle into compose. What we verify here is
+the chunk-1 contract:
+
+  - Dockerfile.gateway builds (multi-stage works, base layers
+    pull, COPYs resolve).
+  - gitleaks, mitmdump are at the documented paths and answer
+    `--version`.
+  - The Python init at /app/gateway_init.py runs and prints the
+    expected "no daemons selected" line when the supervisor is
+    pointed at an empty daemon set.
+
+Skips cleanly when docker is unavailable, or under act_runner
+where the host bind-mount topology breaks multi-stage builds
+that pull large bases.
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import unittest
+
+from tests._docker import skip_unless_docker
+
+
+_IMAGE = "bot-bottle-gateway-test:chunk1"
+_DOCKERFILE = "Dockerfile.gateway"
+
+
+@skip_unless_docker()
+@unittest.skipIf(
+    os.environ.get("GITEA_ACTIONS") == "true",
+    "skipped under act_runner: multi-stage build pulls a 200+MB "
+    "mitmproxy base + two upstream gateway images; runner storage "
+    "+ time budget make this an interactive-only test",
+)
+class TestGatewayImage(unittest.TestCase):
+    """Builds the image once for the class, then runs a few
+    `docker run` probes against it."""
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        repo_root = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+        proc = subprocess.run(
+            ["docker", "build", "-t", _IMAGE,
+             "-f", _DOCKERFILE, "."],
+            cwd=repo_root,
+            stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+        )
+        if proc.returncode != 0:
+            raise unittest.SkipTest(
+                f"docker build failed; skipping image probes.\n"
+                f"{proc.stdout.decode('utf-8', errors='replace')[-2000:]}"
+            )
+
+    @classmethod
+    def tearDownClass(cls) -> None:
+        subprocess.run(
+            ["docker", "image", "rm", "-f", _IMAGE],
+            stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
+        )
+
+    def _run_in_image(self, *cmd: str, timeout: float = 30.0) -> tuple[int, str]:
+        proc = subprocess.run(
+            ["docker", "run", "--rm", "--entrypoint", cmd[0], _IMAGE,
+             *cmd[1:]],
+            stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+            timeout=timeout,
+        )
+        return proc.returncode, proc.stdout.decode("utf-8", errors="replace")
+
+    def test_gitleaks_binary_present_and_versioned(self):
+        rc, out = self._run_in_image("/usr/bin/gitleaks", "version")
+        self.assertEqual(0, rc, msg=out)
+        # gitleaks prints a bare version string like "v8.x.y".
+        self.assertRegex(out, r"v?\d+\.\d+")
+
+    def test_mitmdump_binary_present_and_versioned(self):
+        rc, out = self._run_in_image("mitmdump", "--version")
+        self.assertEqual(0, rc, msg=out)
+        self.assertIn("Mitmproxy", out)
+
+    def test_python_imports_supervise_module(self):
+        # The bundle's supervise daemon imports `supervise` as a
+        # same-directory sibling of `supervise_server`. Probe the
+        # import resolves with `python3 -c` from /app (the
+        # Dockerfile's WORKDIR).
+        rc, out = self._run_in_image(
+            "python3", "-c",
+            "import supervise; import supervise_server; print('ok')",
+        )
+        self.assertEqual(0, rc, msg=out)
+        self.assertIn("ok", out)
+
+    def test_init_supervisor_runs_with_no_daemons(self):
+        # `nothing` matches no canonical daemon → supervisor exits 0
+        # immediately with the documented message. Confirms the
+        # ENTRYPOINT wiring works.
+        proc = subprocess.run(
+            ["docker", "run", "--rm",
+             "-e", "BOT_BOTTLE_GATEWAY_DAEMONS=nothing",
+             _IMAGE],
+            stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+            timeout=10.0,
+        )
+        out = proc.stdout.decode("utf-8", errors="replace")
+        self.assertEqual(0, proc.returncode, msg=out)
+        self.assertIn("no daemons selected", out)
+
+
+if __name__ == "__main__":
+    unittest.main()