build(vendor): rescope the vendored Cordis packages into @deepseek-ai

Machine-produced by `pnpm run rescope-vendor --apply` plus the regeneration it
prints: `pnpm install` for the lockfile, `pnpm run gen-third-party-notices`,
`verify-translation-pairing --write` for the touched bilingual pairs,
`gen-doc-graphs`, and one typert snapshot whose ids embed character offsets.
`pnpm run rescope-vendor --check` verifies the result.

Renames nine vendored packages (cordis, cosmokit, schemastery and the six
@cordisjs plugins) and every reference that resolves them: manifest names and
dependency keys, module specifiers including declare-module merges, cordis.yml
plugin names, tsconfig paths, every Markdown fence, and `docs/` prose.
Directory names, upstream versions, and dependency ranges are unchanged, so
vendor/README.md still reads as an upstream snapshot; its manifest table gains
an upstream-name column so THIRD_PARTY_NOTICES keeps MIT attribution pointed
at each fork's origin.

The tutorial tier follows the rename end to end: its yaml fences named plugins
the Loader can no longer resolve, its `ts ignore-check` fences disagreed with
the compiled fences beside them, and its prose quoted both. The contracts that
told readers to keep upstream names — the root convention and the vendoring
cookbook's tree comment and manifest invariant — now say to rescope instead.

Two rules read `@deepseek-ai/` as "another workspace plugin": the client bundle
purity gate now names the vendored libraries a browser bundle inlines, and the
files where a bare `cordis` is an agent-preset id keep that product data.

packages/scaffold/create-sdk/tests/link-workspace.e2e.ts

@@ -73,7 +73,7 @@ describe.skipIf(!existsSync(builtScripts))('live-linked generated projects', ()
       })
       await writeFile(join(root, 'plugins/probe/src/index.ts'), `
         import { writeFileSync } from 'node:fs'
-        import type { Context } from 'cordis'
+        import type { Context } from '@deepseek-ai/cordis'
         export const name = 'probe'
         export function apply(_ctx: Context): void {
           writeFileSync(new URL('../../../plugin-loaded', import.meta.url), 'loaded\\n')
@@ -119,7 +119,7 @@ describe.skipIf(!existsSync(builtScripts))('live-linked generated projects', ()
       const manifest = JSON.parse(await readFile(join(root, 'package.json'), 'utf8')) as {
         dependencies: Record<string, string>
       }
-      expect(manifest.dependencies.cordis).toMatch(name === 'npm' ? /^file:/ : name === 'pnpm' ? /^link:/ : /^portal:/)
+      expect(manifest.dependencies['@deepseek-ai/cordis']).toMatch(name === 'npm' ? /^file:/ : name === 'pnpm' ? /^link:/ : /^portal:/)
       expect(manifest.dependencies).not.toHaveProperty('node-addon-require-builtin')
     }, 180_000)
   }