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.
