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/api/harness/code-runtime.md

@@ -13,6 +13,26 @@ Semantics every implementation must honor:
 
 [Source](https://github.com/deepseek-harness/deepseek-harness/blob/master/packages/code-runtime/code-runtime/src/index.ts#L59)
 
+### ctx.codeRuntime.language
+
+```ts website-api
+abstract readonly language: string
+```
+
+The source language run expects `program` to be written in, as a lowercase identifier. Informational, not gating — a consumer that generates language-specific presentation (typed SDK stubs, usage instructions) switches on it and fails loud on a language it cannot present. Well-known value: `'typescript'`.
+
+[Source](https://github.com/deepseek-harness/deepseek-harness/blob/master/packages/code-runtime/code-runtime/src/index.ts#L67)
+
+### ctx.codeRuntime.isolation
+
+```ts website-api
+abstract readonly isolation: string
+```
+
+The execution substrate, as a lowercase identifier. Informational, not gating — a descriptor so deployments and diagnostics can tell backends apart, not a security claim. Well-known values: `'worker-thread'`, `'process'`, `'container'`.
+
+[Source](https://github.com/deepseek-harness/deepseek-harness/blob/master/packages/code-runtime/code-runtime/src/index.ts#L75)
+
 ### ctx.codeRuntime.run(request)
 
 ```ts website-api