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).

internal/handler/api_token.go

@@ -17,6 +17,8 @@
 package handler
 
 import (
+	"errors"
+	"io"
 	"net/http"
 	"ragflow/internal/common"
 	"ragflow/internal/dao"
@@ -89,9 +91,10 @@ func (h *SystemHandler) CreateKey(c *gin.Context) {
 
 	tenantID := tenants[0].TenantID
 
-	// Parse request
+	// Parse request. An empty body is valid (all fields are optional);
+	// ShouldBind reports io.EOF for it.
 	var req service.CreateAPIKeyRequest
-	if err = c.ShouldBind(&req); err != nil {
+	if err = c.ShouldBind(&req); err != nil && !errors.Is(err, io.EOF) {
 		common.ResponseWithHttpCodeData(c, http.StatusBadRequest, 400, nil, "Invalid request")
 		return
 	}