联网搜索 maxResults 非整数的诊断上限改为随变体携带，不再写死 5

- WebSearchError::MaxResultsNotInteger 原文案把上限写死成「1 到 5」，同一份文件里 MaxResultsOutOfRange 却是从 DIRECT_TOOL_BRIDGE_MAX_SEARCH_RESULTS 取 {max}；常量一改，两条诊断就会自相矛盾
- 变体加上 max: u64，构造点传 DIRECT_TOOL_BRIDGE_MAX_SEARCH_RESULTS as u64，文案改成「1 到 {max}」
- 只影响这一条诊断的取值来源，判定区间不变

验证：cargo test --bin genarrative-ai-game-creator-shell -- agent::direct_tool_bridge::tests::search_parser_accepts_only_bounded_public_https_results 通过

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

@@ -3417,6 +3417,7 @@ pub(in crate::agent) fn web_search_input(
             .as_u64()
             .ok_or_else(|| WebSearchError::MaxResultsNotInteger {
                 got: value.to_string(),
+                max: DIRECT_TOOL_BRIDGE_MAX_SEARCH_RESULTS as u64,
             })?,
     };
     if !(1..=DIRECT_TOOL_BRIDGE_MAX_SEARCH_RESULTS as u64).contains(&max_results) {

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

@@ -13,7 +13,7 @@ pub(crate) enum WebSearchError {
     QueryEmpty,
     QueryTooLong { got_chars: usize, max_chars: usize },
     QueryHasControlCharacters,
-    MaxResultsNotInteger { got: String },
+    MaxResultsNotInteger { got: String, max: u64 },
     MaxResultsOutOfRange { got: u64, max: u64 },
     ClientUnavailable { cause: String },
     RequestFailed { cause: String },
@@ -47,8 +47,8 @@ impl ToolFailure for WebSearchError {
                 max_chars,
             } => format!("联网搜索失败：query 有 {got_chars} 个字符，超过上限 {max_chars}。"),
             Self::QueryHasControlCharacters => "联网搜索失败：query 含有控制字符。".to_string(),
-            Self::MaxResultsNotInteger { got } => {
-                format!("联网搜索失败：maxResults 必须是 1 到 5 的整数，当前是「{got}」。")
+            Self::MaxResultsNotInteger { got, max } => {
+                format!("联网搜索失败：maxResults 必须是 1 到 {max} 的整数，当前是「{got}」。")
             }
             Self::MaxResultsOutOfRange { got, max } => {
                 format!("联网搜索失败：maxResults={got} 超出范围，必须在 1 到 {max} 之间。")