tests: 300 comes back as "300" from a platform whose key is not an integer

The precedence test wrote `version_code=300` for all five platforms and compared
the desktop's against the int it wrote. It comes back as `"300"`, because the
module preserves each platform's own comparator type instead of flattening both
to int — which is the behaviour the change it was testing had just introduced.

A `coded()` helper now says which shape to expect and why, and the assertion runs
over every non-Android platform rather than spot-checking `linux-deb`. The test
caught a real inconsistency in itself precisely because it compared against a
concrete value rather than round-tripping what it wrote.

tests/test_client_dist.py

@@ -47,6 +47,16 @@ def code_for(platform_id: str):
     return ANDROID_CODE if BY_ID[platform_id].code_is_int else DESKTOP_CODE
 
 
+def coded(platform_id: str, value: int):
+    """`value` in the shape that platform's sidecar carries.
+
+    A test writing `version_code=300` gets `300` back from Android and `"300"` from
+    a desktop platform, because the module preserves each platform's own comparator
+    type rather than flattening both to int.
+    """
+    return value if BY_ID[platform_id].code_is_int else str(value)
+
+
 @pytest.fixture(autouse=True)
 def _empty_baked_client(tmp_path, monkeypatch):
     """Point the baked-in copy at an empty directory.
@@ -306,7 +316,9 @@ def test_precedence_is_decided_per_platform_not_for_the_whole_set():
     place("android", version_code=99)
     found = releases()
     assert found["android"]["version_code"] == 99
-    assert found["linux-deb"]["version_code"] == 300
+    for platform_id in ALL_IDS:
+        if platform_id != "android":
+            assert found[platform_id]["version_code"] == coded(platform_id, 300), platform_id
     assert set(found) == set(ALL_IDS)