refactor: relocate demo app bundles to packages/examples/*-demo

Move the agent-spine bundle and the stdio/ACP/JSON-RPC app packages out of
core/ and ui/ into a new packages/examples/ group, renamed with a -demo
suffix so the npm name marks them as non-product surface:

  core/agent-core   -> examples/agent-spine-demo  (dsh-agent-spine-demo)
  ui/stdio-agent    -> examples/stdio-demo        (dsh-stdio-demo)
  ui/acp-agent      -> examples/acp-demo          (dsh-acp-demo)
  ui/jsonrpc-agent  -> examples/jsonrpc-demo      (dsh-jsonrpc-demo)

Update every code/config/test reference and reference-only doc mentions, and
regenerate module-graph, config-catalog, and doc-graphs. The jsonrpc bin
(dsh-jsonrpc-agent) and single-file exe (dsh-jsonrpc-agent-pkg) keep their
names; the SDK runtime-startup surface is reconciled separately.

packages/examples/stdio-demo/src/bin.ts

@@ -0,0 +1,19 @@
+#!/usr/bin/env node
+/**
+ * Boot a stdio app from a leaf `cordis.yml`; usage is `dsh-stdio-demo [config]`, defaulting to the
+ * cwd file. Shared `.env` loading, fail-loud Loader guards, and settled-tree boot live in
+ * dsh-app-boot. The echo and REPL demos invoke this bin with their own leaf configs.
+ * @module @deepseek-ai/dsh-stdio-demo/bin
+ */
+
+import { boot, installFailLoud, loadEnv, resolveConfigPath } from '@deepseek-ai/dsh-app-boot'
+
+const NAME = 'dsh-stdio-demo'
+
+/* v8 ignore start -- thin self-executing composition over the unit-tested
+   dsh-app-boot helpers; exercised end-to-end by the keyless Loader-path and
+   built-bin smokes */
+installFailLoud(NAME)
+loadEnv(NAME)
+await boot(NAME, resolveConfigPath(process.argv[2] ?? './cordis.yml', undefined))
+/* v8 ignore stop */