refactor(git-gate): centralize hostname qualification in globalize_slug

Adds globalize_slug(slug) to bottle_state alongside bottle_identity.
git_gate_provision now calls globalize_slug(slug) instead of inlining
socket.gethostname(), so the hostname-qualification logic has a single,
named home. Assumes slug is a mint_slug output.

Title format changes from bot-bottle:{host}:{slug}:{name}
to bot-bottle:{host}-{slug}:{name} to match the globalize_slug contract.

tests/unit/test_git_gate_render_provision.py

@@ -127,9 +127,9 @@ class TestProvisionDynamicKey(unittest.TestCase):
             self.assertEqual(b"PRIVATE-KEY-BYTES", key_file.read_bytes())
             id_file = Path(d) / "repo-deploy-key-id"
             self.assertEqual("kid123", id_file.read_text())
-        # owner_repo had .git stripped; title carries hostname + slug + name
+        # owner_repo had .git stripped; title carries globalize_slug(slug) + name
         hostname = socket.gethostname()
-        self.assertEqual([("o/r", f"bot-bottle:{hostname}:myslug:repo")], fake.created)
+        self.assertEqual([("o/r", f"bot-bottle:{hostname}-myslug:repo")], fake.created)
 
     def test_missing_token_raises(self) -> None:
         with tempfile.TemporaryDirectory() as d, \