Clean up examples (#182)

* Centralize example server transport logic in shared utils

Move stdio/HTTP transport handling into `server-utils.ts` so example
servers only need to call `startServer(createServer)`. Switch HTTP
transport to stateless mode and remove legacy SSE endpoints.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Make example servers self-contained with local server-utils

Copy `server-utils.ts` into each example's `src/` directory so examples
can be used standalone without the shared directory. Updates imports
from `"../shared/server-utils.js"` to `"./src/server-utils.js"`.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Add `integration-server` example for E2E testing

Add dedicated `integration-server` example (duplicated from
`basic-server-react`) to preserve E2E testing capabilities while
allowing `basic-server-react` to be simplified as a minimal example.

Changes:
- Add `examples/integration-server` exercising SDK communication APIs
- Update E2E tests to use `integration-server` instead of
  `basic-server-react` and `basic-server-vanillajs`
- Use server name labels instead of indices for more robust test
  selection
- Remove `basic-react.png` and `basic-vanillajs.png` golden snapshots

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Co-Authored-By: Claude <noreply@anthropic.com>

* Simplify `basic-server-*` examples

- Clarify comments
- Return plain text from `get-time` tool instead of JSON
- Remove simulated cleanup delay from `onteardown`

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

examples/basic-server-vanillajs/src/mcp-app.ts

@@ -15,12 +15,8 @@ const log = {
 
 
 function extractTime(result: CallToolResult): string {
-  const text = result.content!
-    .filter((c): c is { type: "text"; text: string } => c.type === "text")
-    .map((c) => c.text)
-    .join("");
-  const { time } = JSON.parse(text) as { time: string };
-  return time;
+  const { text } = result.content?.find((c) => c.type === "text")!;
+  return text;
 }
 
 
@@ -40,8 +36,6 @@ const app = new App({ name: "Get Time App", version: "1.0.0" });
 
 app.onteardown = async () => {
   log.info("App is being torn down");
-  await new Promise((resolve) => setTimeout(resolve, 500)); // Simulate cleanup work
-  log.info("App teardown complete");
   return {};
 };