website: fix nine review findings (generator coverage, loader facts, mode semantics)

Generator (all four structural gaps):
- harness service pages now render public properties/accessors, not just
  methods (ctx.codeRuntime.language/isolation were missing);
- the class page merges the same-named interface half, so ctx.root/baseUrl/
  events/logger/reflect/registry appear on Context (vendor root JSDoc gains
  prose alongside @experimental);
- Pick<…> heritage on a Context merge resolves to the picked class members,
  giving ctx.effect a documented signature on the Fiber page;
- {@link} tags normalize to code spans; merge sections get their own h2 so
  reflect members no longer nest under 'Static members'.

verify-website-yaml: reject the unloadable 'group:' pseudo-name (tree.import
only special-cases 'cordis:'; no builtin is registered here) and recurse into
@cordisjs/plugin-group nested entry lists instead.

Prose corrected against loader/cordis source: service.md isolation example
uses the real group plugin + group: true + the required isolate map;
config.md documents concurrent entry startup (Promise.all; order via inject)
and the real hmr defaults (root ['.'], base/ignored/debounce); events.md
fixes emit (synchronous, not parallel), bail (null/false also delegate), and
serial (stops at the first bail value).

website/zh-CN/develop/framework/events.md

@@ -45,7 +45,7 @@ Cordis 提供多种事件触发模式，适用于不同场景：
 
 ### emit — 广播
 
-所有监听器并行执行，不关心返回值：
+同步依次调用所有监听器，不等待、不关心返回值（监听器如果是 async，其 Promise 被忽略）：
 
 ```ts
 import type { Context } from 'cordis'
@@ -71,7 +71,7 @@ ctx.on('my-plugin/turn-end', (agentId, turnIndex) => {
 
 ### bail — 短路
 
-依次调用监听器，第一个返回非 `undefined` 值的结果作为最终值：
+同步依次调用监听器，第一个返回**非 `undefined`/`null`/`false`** 值的监听器终止链并作为最终值（返回 `undefined`/`null`/`false` 则继续下一个）：
 
 ```ts
 import type { Context } from 'cordis'
@@ -99,7 +99,7 @@ ctx.on('some-check', (input) => {
 
 ### serial — 顺序执行
 
-所有监听器按注册顺序依次执行（异步安全）：
+按注册顺序逐个 `await` 监听器，遇到第一个 bail 值（非 `undefined`/`null`/`false`）即停止并返回它；全部返回空值则执行到底。相当于 `bail` 的异步版：
 
 ```ts
 import type { Context } from 'cordis'