fix: stop dropping tolerance when converting a group to Smart (#2112)

The Smart override converts url-test and load-balance groups and then
strips their type-specific keys. tolerance is in that list, but the Smart
core supports it: SmartOption.Tolerance feeds the sort comparator, where
delays within tolerance compare equal so the group stops flapping between
nodes of near-identical latency.

Because a normal override always runs before the Smart one, this leaves no
way to set tolerance at all while the auto override is on - a value in the
subscription is deleted, and so is one set by an earlier override. The
branch that handles an already-smart group never deleted it, so the two
paths disagreed.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

src/main/config/smartOverride.ts

@@ -86,10 +86,9 @@ function main(config) {
             group.uselightgbm = ${useLightGBM}
             group.collectdata = ${collectData}
             
-            // 移除 url-test 和 load-balance 特有的配置
+            // 移除 url-test 和 load-balance 特有的配置（tolerance 是 Smart 也支持的选项，保留）
             if (group.url) delete group.url
             if (group.interval) delete group.interval
-            if (group.tolerance) delete group.tolerance
             if (group.lazy) delete group.lazy
             if (group.expected_status) delete group['expected-status']
           }