Remove stray .snap.new filtering from schema fixtures reader

Motivation:
- `codex-app-server-protocol` schema fixtures are not insta snapshots.
- Filtering `*.snap.new` is confusing and risks hiding real files.

What changed:
- Remove the `.snap.new` filename special case in `read_schema_fixture_tree`.

Refs: macOS Bazel schema fixture mismatch investigation

codex-rs/app-server-protocol/schema/json/ChatgptAuthTokensRefreshParams.json

@@ -0,0 +1,33 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "ChatgptAuthTokensRefreshReason": {
+      "oneOf": [
+        {
+          "description": "Codex attempted a backend request and received `401 Unauthorized`.",
+          "enum": [
+            "unauthorized"
+          ],
+          "type": "string"
+        }
+      ]
+    }
+  },
+  "properties": {
+    "previousAccountId": {
+      "description": "Workspace/account identifier that Codex was previously using.\n\nClients that manage multiple accounts/workspaces can use this as a hint to refresh the token for the correct workspace.\n\nThis may be `null` when the prior ID token did not include a workspace identifier (`chatgpt_account_id`) or when the token could not be parsed.",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "reason": {
+      "$ref": "#/definitions/ChatgptAuthTokensRefreshReason"
+    }
+  },
+  "required": [
+    "reason"
+  ],
+  "title": "ChatgptAuthTokensRefreshParams",
+  "type": "object"
+}