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.

examples/coding-agent/cordis.yml

@@ -1,4 +1,4 @@
-# REPL agent with swappable DeepSeek and local-bash backends. `dsh-stdio-agent`
+# REPL agent with swappable DeepSeek and local-bash backends. `dsh-stdio-demo`
 # supplies the agent-core spine, logging, JSONL persistence, readline UI, and `main` agent.
 # HMR remains a leaf because it requires Loader internals; `demo:repl` passes
 # `--expose-internals`. The app bin loads the gitignored root `.env`; this file
@@ -29,7 +29,7 @@
 
 # The app bundle pre-creates the REPL's `main` agent.
 - id: stdio-agent
-  name: '@deepseek-ai/dsh-stdio-agent'
+  name: '@deepseek-ai/dsh-stdio-demo'
   config:
     model: deepseek-v4-flash
     # Set RESUME_SESSION_ID to continue a prior persisted session (the ids live