fix: register the examples/ group in the tsconfig paths map

The @deepseek-ai/dsh-* wildcard maps each package name to its group's
src; the new packages/examples/ group needs its own glob, or the four
moved packages fall back to unbuilt lib/ and vitest cannot resolve them.
Also update the moved specs' plugin export-name assertions (acp-agent ->
acp-demo, stdio-agent -> stdio-demo, agent-core -> agent-spine-demo).

packages/examples/stdio-demo/tests/stdio-agent.spec.ts

@@ -127,7 +127,7 @@ describe('dsh-stdio-demo app', () => {
   })
 
   it('exposes its name and Config schema', () => {
-    expect(stdioAgent.name).toBe('stdio-agent')
+    expect(stdioAgent.name).toBe('stdio-demo')
     expect(stdioAgent.Config).toBeDefined()
   })
 
@@ -161,7 +161,7 @@ describe('dsh-stdio-demo app', () => {
     const loader = Object.create(Loader.prototype) as Loader
     const unwrapped = loader.unwrapExports(stdioAgent) as Record<string, unknown>
     expect(unwrapped).toBe(stdioAgent)
-    expect(unwrapped.name).toBe('stdio-agent')
+    expect(unwrapped.name).toBe('stdio-demo')
     expect(unwrapped.Config).toBeDefined()
     expect(typeof unwrapped.apply).toBe('function')
   })