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).

cmd/ragflow_server.go

@@ -444,6 +444,8 @@ func runAdmin(ctx context.Context, args *serverArgs, config *server.Config) erro
 
 	// Create Gin engine
 	ginEngine := gin.New()
+	// Mirror Quart's merge_slashes: collapse duplicate slashes before routing.
+	ginEngine.RemoveExtraSlash = true
 
 	// Middleware
 	ginEngine.Use(common.GinLogger())
@@ -848,6 +850,8 @@ func startServer(ctx context.Context, config *server.Config) {
 
 	// Create Gin engine
 	ginEngine := gin.New()
+	// Mirror Quart's merge_slashes: collapse duplicate slashes before routing.
+	ginEngine.RemoveExtraSlash = true
 
 	// Middleware
 	// Note: common.GinLogger() is registered inside router.Setup so the