[auth] Implement CIMD conformance test (#37)

* add cimd test and negative test

* Improve auth-test-no-cimd.ts documentation for clarity

Address review feedback: expanded comments to better explain what CIMD is,
why this client is non-compliant, and what behavior it's testing.

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

* Remove .js extensions from relative imports

tsx doesn't require .js extensions for TypeScript imports.
Keeps .js for @modelcontextprotocol/sdk imports as those are external packages.

Also improves auth-test-no-cimd.ts documentation for clarity.

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

* Skip auth/basic-cimd test until SDK support lands

Waiting on typescript-sdk PR #1127 for CIMD support.

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

* Fix trailing whitespace in auth-test-no-cimd.ts

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

src/checks/client.ts

@@ -1,4 +1,4 @@
-import { ConformanceCheck, CheckStatus } from '../types.js';
+import { ConformanceCheck, CheckStatus } from '../types';
 
 export function createServerInfoCheck(serverInfo: {
   name: string;