test: update test suite for git-gate manifest redesign (PRD 0047)

- fixtures.py: fixture_with_git_dict uses git-gate.repos + url/identity/host_key
- test_manifest_git: rewrite to use git-gate.repos; replace duplicate-name
  test (names = dict keys, always unique) with two-repos-different-hosts test
- test_manifest_git_user: _manifest → git-gate.user; update error message assertions
- test_manifest_agent_git_user: git → git-gate throughout; repos rejection test
- test_manifest_extends: git.remotes/git.user → git-gate.repos/git-gate.user
- test_provision_git: IP test updated — no host alias, single insteadOf
- test_compose: git.remotes → git-gate.repos + new field names
- test_docker_provision_git_user: git.user → git-gate.user
- test_git_gate: inline manifest dict updated to git-gate.repos
- test_smolmachines_provision: git_json → git_gate_json; remove _remote_host

tests/unit/test_git_gate.py

@@ -220,11 +220,10 @@ class TestPrepare(unittest.TestCase):
 
     def test_prepare_skips_known_hosts_file_when_key_missing(self):
         manifest = Manifest.from_json_obj({
-            "bottles": {"dev": {"git": {"remotes": {
-                "github.com": {
-                    "Name": "foo",
-                    "Upstream": "ssh://git@github.com/didericis/foo.git",
-                    "IdentityFile": "/dev/null",
+            "bottles": {"dev": {"git-gate": {"repos": {
+                "foo": {
+                    "url": "ssh://git@github.com/didericis/foo.git",
+                    "identity": "/dev/null",
                 },
             }}}},
             "agents": {"demo": {"skills": [], "prompt": "", "bottle": "dev"}},