fix(frontend): remove test types from base tsconfig for CI build

The base tsconfig.json had types: ["vitest/globals", "@testing-library/jest-dom/vitest"]
which are devDependencies only installed during development. CI production
builds with npm ci --production don't include these, causing TS2688 errors.

Solution:

Remove types array from tsconfig.json (let TS auto-discover available types)
Simplify tsconfig.build.json to only exclude test files
Add triple-slash type references to test setup file
Add typecheck config to vitest.config.ts
This ensures:

Production builds work without devDependencies
Test files still have proper type definitions
No JSX.IntrinsicElements errors from missing React types

frontend/src/api/__tests__/dnsProviders.test.ts

@@ -199,7 +199,7 @@ describe('createDNSProvider', () => {
     })
 
     await expect(
-      createDNSProvider({ ...validRequest, provider_type: 'invalid' as any })
+      createDNSProvider({ ...validRequest, provider_type: 'invalid' as DNSProviderRequest['provider_type'] })
     ).rejects.toMatchObject({
       response: { status: 400 },
     })