feat(server): add proactive channel probes and load-aware stable routing / 服务端新增主动探活与负载感知稳定路由 (#330)

* wip: preserve local changes before upstream merge

* Improve proxy routing stability and add stable-first strategy

* Sync explicit-group routing strategy to eligible source routes

* Fix proxy retry and runtime health review issues

* fix: make proxy channel retry attempts configurable

* fix: harden proxy retry recovery and bookkeeping

* fix: address pr 257 review comments

* feat(proxy): add sticky session channel coordination

* feat(server): add proactive channel probes and load-aware stable routing

* test(server): stabilize session load routing selection assertion

* fix(proxy): harden codex forwarding stability

* fix(router): rotate stable-first channels by healthy order

* fix(server): address probe review feedback

* fix(server): address probe review follow-ups

* fix(ci): address CodeQL and core test failures

* feat(server): refine stable-first routing recovery and observation

* Finish PR 330 settings and review fixes

* Fix chat site endpoint CI mock

* Address latest PR 330 review comments

---------

Co-authored-by: Cita <juricek.chen@gmail.com>

src/web/i18n.supplement.ts

@@ -41,6 +41,7 @@ export const zhToEnSupplemental: Record<string, string> = {
   '按成本、延迟、成功率自动选择最优通道，故障自动转移': 'Automatically select the optimal channel based on cost, delay, and success rate, and automatically transfer failures',
   '按模型过滤': 'Filter by model',
   '按权重随机（W=${weight}，成本=${costSourceText}:${(cost?.unitCost || 1).toFixed(6)}，同站点通道=${siteChannels}，概率≈${(probability * 100).toFixed(1)}%）': 'Randomly by weight (W=${weight}, cost=${costSourceText}:${(cost?.unitCost || 1).toFixed(6)}, same-site channel=${siteChannels}, probability≈${(probability * 100).toFixed(1)}%)',
+  'P 值是硬优先级，只会在当前最高可用优先级内结合权重、成本和健康度随机选择': 'P value is a hard priority. Selection stays within the highest available priority tier, then chooses randomly using weight, cost, and health signals.',
   '保存': 'save',
   '保存 Cookie': 'Save Cookie',
   '保存 Cookie 失败': 'Failed to save cookie',
@@ -573,6 +574,7 @@ export const zhToEnSupplemental: Record<string, string> = {
   '系统会根据模型可用性自动生成路由。优先级按 P0/P1 等桶管理，同一桶内可有多个通道；拖动通道或灰色分隔线即可调整。精确模型路由会自动过滤只支持该模型的账号和令牌。群组路由中的优先级调整会直接回写来源通道。选中概率表示请求到达时该通道被选中的概率。成本来源优先级为：实测成本 → 账号配置成本 → 目录参考价 → 默认回退单价。': 'The system automatically generates routes based on model availability. Priorities are managed as P0/P1 buckets, and multiple channels can share the same bucket; drag channels or the gray separators to adjust them. Exact model routes automatically filter accounts and tokens that only support that model. Priority edits inside group routes write back to the source channels directly. The selection probability indicates the probability of the channel being selected when the request arrives. The priority of cost sources is: measured cost → account configuration cost → catalog reference price → default fallback unit price.',
   '该群组会将多个来源模型聚合为一个对外模型名；这里调整优先级桶时会直接回写来源通道。若某个来源模型被其他群组复用，保存前会提示影响范围。': 'This group aggregates multiple source models into one public model name. Priority bucket edits here write back to the source channels directly. If a source model is reused by other groups, the impact is shown before saving.',
   '通配符路由按请求实时决策；下方优先级桶在整条路由内全局生效，来源模型只作为通道标签展示。': 'Wildcard routes decide per request. The priority buckets below apply globally across the whole route, while source models are shown only as channel labels.',
+  '系统会根据模型可用性自动生成路由；精确模型路由会自动过滤只支持该模型的账号和令牌。': 'Routes are auto-generated by model availability; exact model routes auto-filter accounts and tokens that support that model.',
   '系统设置': 'System settings',
   '显示调试': 'show debugging',
   '项目链接': 'Project link',
@@ -588,10 +590,16 @@ export const zhToEnSupplemental: Record<string, string> = {
   '选择站点': 'Select site',
   '选择账号': 'Select account',
   '选择账号后同步站点令牌': 'Synchronize site token after selecting account',
+  '选中概率用于解释当前策略下这一次请求更可能落到哪里；轮询和稳定优先更适合把它当作顺序参考。': 'Selection probability explains where this request is more likely to land under the current strategy; for round robin and stable first it is better treated as an order hint.',
+  '先避开最近失败或不健康站点，再在稳定池里按顺序轮询；P 值表示轮询顺位': 'Avoid recently failed or unhealthy sites first, then rotate through the stable pool in order; P value means rotation order.',
   '讯飞星火': 'iFlytek Spark',
   '延迟': 'Delay',
   '验证': 'verify',
   '验证 Token': 'Verify Token',
+  '只要更高优先级还有可用通道，后面的通道本次就不会参与选择。': 'As long as a higher-priority tier still has available channels, later channels will not participate in this selection.',
+  '忽略 P 值，按全局顺序依次调用；连续失败 3 次后进入分级冷却': 'Ignore P value and call in global order; after 3 consecutive failures the channel enters staged cooldown.',
+  '当前策略不看 P 值；如果之后切回其他策略，拖拽保存的顺序仍会保留。': 'This strategy does not use P value; if you switch back to other strategies later, the saved drag order is still kept.',
+  '当前策略下，稳定站点会按 P 顺序轮换；不稳定站点会被自动降权或临时避让。': 'Under this strategy, stable sites rotate by P order; unstable sites are automatically downweighted or temporarily avoided.',
   '验证成功: ${result.userInfo?.username || \'未知用户\'}': 'Verification successful: ${result.userInfo?.username || \'未知用户\'}',
   '验证失败': 'Authentication failed',
   '验证中...': 'Verifying...',