build: doc-sync gates — typecheck doc code blocks + verify event taxonomy (RFC 006 pts 1-2)

Two tsx CI gates make doc/code drift fail fast:
- doc-typecheck extracts every fenced ts block from README/docs/package READMEs,
  compiles them with tsc --noEmit against a temp project (vendor->lib, harness->src
  paths from tsconfig.typecheck.json), and fails on errors. Deliberate sketches opt
  out with ```ts ignore-check; the opt-out ratio is reported and capped.
- verify-event-taxonomy asserts the docs/architecture.md taxonomy table names
  exactly the events declared in the interface Events blocks. This surfaced three
  events the table had been missing (tools/change, llm/adapter-change,
  system-prompt/change), now added.

Doc snippets made compilable with stub imports/declares (1 genuine sketch ignored).
Wired into CI after typecheck. API reports (RFC 006 pt 3) deferred. Graduates RFC
006 pts 1-2 -> ADR 0014.

docs/cookbook/adding-a-tool.md

@@ -5,6 +5,7 @@ How to give the model a new capability. Reference implementations: `examples/ech
 ## The minimal shape
 
 ```ts
+import { readFile } from 'node:fs/promises'
 import type { Context } from 'cordis'
 import { defineTool } from '@deepseek-ai/dsh-tools'
 

docs/cookbook/adding-an-llm-adapter.md

@@ -4,7 +4,7 @@ How to connect a new model provider. Reference implementations: `packages/llm-de
 
 ## The shape
 
-```ts
+```ts ignore-check
 class MyAdapter extends LlmAdapter {
   async * stream(options: GenerateOptions): AsyncIterable<StreamChunk> { … }
 }

docs/cookbook/extension-cookbook.md

@@ -11,6 +11,11 @@ A tool registers on `ctx.tools`. The annotated `defineTool` example (typed `exec
 A hook wraps the `tools/execute` waterfall to veto or rewrite a call — the seam where sandbox, permission, and plan-mode plugins live.
 
 ```ts
+import type { Context } from 'cordis'
+import type { ToolExecution } from '@deepseek-ai/dsh-tools'
+
+declare function isAllowed(exec: ToolExecution): Promise<boolean>
+
 export const name = 'permission-gate'
 
 export function apply(ctx: Context) {
@@ -32,6 +37,11 @@ export function apply(ctx: Context) {
 A UI plugin consumes `agent/stream-chunk` and session events for rendering, and drives input back in via `agent.send()` / `agent.steer()`.
 
 ```ts
+import type { Context } from 'cordis'
+
+declare function render(text: string): void
+declare function onUserInput(handler: (text: string) => void): void
+
 export const name = 'my-ui'
 export const inject = ['agents']