Test: release Go-proxy RESTful contract tests verified passing in Go mode (#17468)

### Summary

Aligns Go and Python error codes/messages so both backends honor the
same RESTful API contract, removing implementation-specific error leaks
(MySQL errors, `ValueError`, `AttributeError`, Gin validator format) in
favor of clean business error codes.

**Chat list** — invalid `orderby` now returns code 101 (was: raw Python
`AttributeError` code 100); invalid `page`/`page_size` values fall back
to defaults (was: raw `ValueError`/`ProgrammingError` code 100).

**Dataset create/update/delete** — adds UUID validation (101),
extra-field rejection (101), duplicate-id detection (101), content-type
/ JSON-syntax / object-shape checks (101), and "lacks permission" for
nonexistent datasets (IDOR). Create auto-deduplicates dataset names.
Pagerank updates tolerate a missing ES index. List response includes
`parser_config` and `pagerank`.

**Session list/update** — adds filtering, sorting, and pagination
support. Empty payloads are valid no-ops. Authorization errors map to
code 109.

**Chunk list** — doc object uses Python key names (`chunk_count`,
`dataset_id`, `chunk_method`, run text status). Add validates list
element types.

**Document update** — adds `chunk_method` alias, pydantic-style Field
error messages, metadata index auto-create with refresh, and "These
documents do not belong to dataset" messages. List validates
`metadata_condition` and reports ownership errors for unmatched name/id
filters.

**Search completion** — `kb_ids` ownership failure returns code 102
instead of 109.

Released 31 contract tests from `GO_ONLY_SKIPS` (all verified passing on
both Go and Python backends with real LLM keys).

test/testcases/restful_api/test_documents.py

@@ -289,36 +289,36 @@ def test_documents_list_error_and_sorting_contract(rest_client, create_dataset,
             "orderby invalid",
             f"/datasets/{dataset_id}/documents",
             {"orderby": "unknown"},
-            100,
-            "Document' has no attribute 'unknown'",
+            101,
+            "invalid orderby field",
         ),
         (
             "page invalid number",
             f"/datasets/{dataset_id}/documents",
             {"page": -1, "page_size": 2},
-            100,
-            "1064",
+            0,
+            "",
         ),
         (
             "page invalid type",
             f"/datasets/{dataset_id}/documents",
             {"page": "a", "page_size": 2},
-            100,
-            "invalid literal for int()",
+            0,
+            "",
         ),
         (
             "page_size invalid number",
             f"/datasets/{dataset_id}/documents",
             {"page_size": -1},
-            100,
-            "1064",
+            0,
+            "",
         ),
         (
             "page_size invalid type",
             f"/datasets/{dataset_id}/documents",
             {"page_size": "a"},
-            100,
-            "invalid literal for int()",
+            0,
+            "",
         ),
     ]
     for case_name, path, params, expected_code, expected_message in error_cases:
@@ -547,7 +547,7 @@ def test_documents_update_name_contract(rest_client, create_dataset, tmp_path):
         ("new_name.txt", 0, ""),
         (long_name, 0, ""),
         (0, 102, "Field: <name> - Message: <Input should be a valid string> - Value: <0>"),
-        (None, 100, "AttributeError('NoneType' object has no attribute 'encode')"),
+        (None, 102, "Field: <name> - Message: <Input should be a valid string> - Value: <None>"),
         ("", 101, "The extension of file can't be changed"),
         ("ragflow_test_upload_0", 101, "The extension of file can't be changed"),
         ("ragflow_test_upload_1.txt", 102, "Duplicated document name in the same dataset."),