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/support/acp-snapshot/README.md

@@ -21,7 +21,7 @@ const SCENARIOS: Scenario[] = [
 
 defineAcpSnapshotSuite({
   agent: { // absolute paths, resolved from the suite's own location
-    binScript: fileURLToPath(new URL('../../../packages/ui/acp-agent/src/bin.ts', import.meta.url)),
+    binScript: fileURLToPath(new URL('../../../packages/examples/acp-demo/src/bin.ts', import.meta.url)),
     configPath: fileURLToPath(new URL('../cordis.yml', import.meta.url)),
     tsconfigPath: fileURLToPath(new URL('../../../tsconfig.json', import.meta.url)),
   },

packages/support/acp-snapshot/src/harness.ts

@@ -37,7 +37,7 @@ const tsxLoader = fileURLToPath(import.meta.resolve('tsx'))
  * them from its own `import.meta.url`.
  */
 export interface AgentUnderTest {
-  /** The agent bin entry (e.g. `packages/ui/acp-agent/src/bin.ts`), run unbuilt via tsx. */
+  /** The agent bin entry (e.g. `packages/examples/acp-demo/src/bin.ts`), run unbuilt via tsx. */
   binScript: string
   /**
    * The example's live `cordis.yml`. Under `DSH_SNAPSHOT=replay` the bin swaps