回退列表工具 offset 上限的收窄，agc_list_registered_assets 恢复无上限

- 回退 4e5adb2a3：page 的 max_offset 恢复成 Option<usize>，删掉 TOOL_PAGE_MAX_OFFSET 常量
- agc_list_registered_assets 传 None（offset 无上限，与它原本的行为一致），agc_list_project_files / agc_list_account_assets 仍传原来的 Some(500)
- agc_list_registered_assets 的 inputSchema offset 去掉 maximum: 500，恢复到原公开入参范围

验证：cargo test --bin genarrative-ai-game-creator-shell -- agent::direct_tool_bridge:: 41 passed / 0 failed

apps/ai-game-creator-shell/src-tauri/src/agent/direct_tool_bridge.rs

@@ -1,8 +1,6 @@
 use super::*;
 use crate::agent::tool::apply_patch::error::ApplyPatchError;
-use crate::agent::tool::arguments::{
-    optional_text, page, required_text, ToolPage, ToolTextField, TOOL_PAGE_MAX_OFFSET,
-};
+use crate::agent::tool::arguments::{optional_text, page, required_text, ToolPage, ToolTextField};
 use crate::agent::tool::browser_playtest::error::BrowserPlaytestError;
 #[cfg(all(windows, feature = "cocos-editor-execute"))]
 use crate::agent::tool::cocos_execute::error::CocosExecuteError;
@@ -1212,7 +1210,7 @@ pub(in crate::agent) fn list_registered_assets_input(
         arguments,
         50,
         DIRECT_TOOL_BRIDGE_MAX_RESOURCE_PAGE_SIZE,
-        TOOL_PAGE_MAX_OFFSET,
+        None,
     )?;
     Ok(ListRegisteredAssetsInput {
         kind,
@@ -1566,7 +1564,7 @@ pub(in crate::agent) fn list_project_files_input(
         arguments,
         100,
         DIRECT_TOOL_BRIDGE_MAX_RESOURCE_PAGE_SIZE,
-        TOOL_PAGE_MAX_OFFSET,
+        Some(500),
     )?;
     Ok(ListProjectFilesInput {
         path,
@@ -1991,7 +1989,7 @@ pub(in crate::agent) fn list_account_assets_input(
         arguments,
         100,
         DIRECT_TOOL_BRIDGE_MAX_RESOURCE_PAGE_SIZE,
-        TOOL_PAGE_MAX_OFFSET,
+        Some(500),
     )?;
     Ok(ListAccountAssetsInput {
         folder_id,

apps/ai-game-creator-shell/src-tauri/src/agent/direct_tools_mcp.rs

@@ -405,7 +405,7 @@ fn direct_tools_mcp_specs_for_plugins(
                             "default": false,
                             "description": prompt_text!("directTools.agc_list_registered_assets.parameters.includeSequenceFrames")
                         },
-                        "offset": { "type": "integer", "minimum": 0, "maximum": 500, "default": 0 },
+                        "offset": { "type": "integer", "minimum": 0, "default": 0 },
                         "limit": { "type": "integer", "minimum": 1, "maximum": 100, "default": 50 }
                     },
                     "additionalProperties": false

apps/ai-game-creator-shell/src-tauri/src/agent/tool/arguments.rs

@@ -57,18 +57,12 @@ pub(crate) struct ToolPage {
     pub limit: usize,
 }
 
-/// 三个列表工具共用的 `offset` 上限：每个调用点都必须显式传值，避免某一路悄悄不设上限。
-///
-/// 取值与 `agc_list_project_files` / `agc_list_account_assets` 的 inputSchema
-/// `offset.maximum` 一致；`agc_list_registered_assets` 的 schema 同步为同一个值。
-pub(crate) const TOOL_PAGE_MAX_OFFSET: usize = 500;
-
 /// 解析 `offset`/`limit`。分页规则在三个列表工具之间一致，只有默认值与上限不同。
 pub(crate) fn page(
     arguments: &Value,
     default_limit: usize,
     max_limit: usize,
-    max_offset: usize,
+    max_offset: Option<usize>,
 ) -> Result<ToolPage, ToolPageRejection> {
     let offset = arguments
         .get("offset")
@@ -83,11 +77,8 @@ pub(crate) fn page(
         })
         .transpose()?
         .unwrap_or(0);
-    if offset > max_offset {
-        return Err(ToolPageRejection::OffsetTooLarge {
-            got: offset,
-            max: max_offset,
-        });
+    if let Some(max) = max_offset.filter(|max| offset > *max) {
+        return Err(ToolPageRejection::OffsetTooLarge { got: offset, max });
     }
     let limit = arguments
         .get("limit")