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/ToolRequestUserInputResponse.json

@@ -0,0 +1,34 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "ToolRequestUserInputAnswer": {
+      "description": "EXPERIMENTAL. Captures a user's answer to a request_user_input question.",
+      "properties": {
+        "answers": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "answers"
+      ],
+      "type": "object"
+    }
+  },
+  "description": "EXPERIMENTAL. Response payload mapping question ids to answers.",
+  "properties": {
+    "answers": {
+      "additionalProperties": {
+        "$ref": "#/definitions/ToolRequestUserInputAnswer"
+      },
+      "type": "object"
+    }
+  },
+  "required": [
+    "answers"
+  ],
+  "title": "ToolRequestUserInputResponse",
+  "type": "object"
+}