chore: delete pipelock files and strip from manifest layer

- Delete bot_bottle/pipelock.py, backend/docker/pipelock.py,
  backend/docker/pipelock_apply.py
- Delete all pipelock unit/integration/canary tests
- Remove PipelockRoutePolicy from manifest_egress.py; drop the
  Pipelock field from EgressRoute and the 'pipelock' key from
  EgressRoute.from_dict
- Remove PipelockRoutePolicy re-export from manifest.py __all__

tests/canaries/test_pipelock_image.py

@@ -1,45 +0,0 @@
-"""Canary: the pinned pipelock image's binary actually runs.
-
-This test exists to catch a broken upstream packaging at the pinned
-digest. It is NOT part of the per-push suite — that would couple every
-dev push to upstream registry availability. Set
-BOT_BOTTLE_RUN_CANARIES=1 to opt in (a scheduled CI workflow does
-this; humans can run it ad-hoc the same way).
-"""
-
-import os
-import subprocess
-import unittest
-
-from bot_bottle.backend.docker.pipelock import PIPELOCK_IMAGE
-from tests._docker import skip_unless_docker
-
-
-@unittest.skipUnless(
-    os.environ.get("BOT_BOTTLE_RUN_CANARIES") == "1",
-    "canary suite is opt-in; set BOT_BOTTLE_RUN_CANARIES=1 to run",
-)
-@skip_unless_docker()
-class TestPipelockImage(unittest.TestCase):
-    @classmethod
-    def setUpClass(cls):
-        result = subprocess.run(
-            ["docker", "pull", PIPELOCK_IMAGE],
-            stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL,
-            check=False,
-        )
-        if result.returncode != 0:
-            raise unittest.SkipTest(f"could not pull {PIPELOCK_IMAGE}")
-
-    def test_binary_runs(self):
-        result = subprocess.run(
-            ["docker", "run", "--rm", PIPELOCK_IMAGE, "--version"],
-            capture_output=True, text=True, check=False,
-        )
-        out = result.stdout + result.stderr
-        self.assertRegex(out, r"[Pp]ipelock|2\.[0-9]+\.[0-9]+")
-
-
-if __name__ == "__main__":
-    unittest.main()