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_compose.py

@@ -49,11 +49,10 @@ def _manifest(*, supervise: bool, with_git: bool, with_egress: bool) -> Manifest
     if supervise:
         bottle["supervise"] = True
     if with_git:
-        bottle["git"] = {"remotes": {
-            "example.com": {
-                "Name": "upstream",
-                "Upstream": "ssh://git@example.com:22/x/y.git",
-                "IdentityFile": "/etc/hostname",  # any existing file
+        bottle["git-gate"] = {"repos": {
+            "upstream": {
+                "url": "ssh://git@example.com:22/x/y.git",
+                "identity": "/etc/hostname",  # any existing file
             },
         }}
     if with_egress: