feat: Introduce API versioning and compatibility headers

[Glam26]

I have completed the task. Here's a summary of the changes:

1. API Versioning & Deprecation Header: I added a global onSend hook in
   Fastify ( apps/access-api/src/app.ts ) that adds the x-guildpass-api-
   version: 1.0.0 header to all API responses. It also surfaces a
   deprecation: true header if a route explicitly marks itself as deprecated
   via its schema definition.
2. Health Endpoint Output: Updated the GET /health/live endpoint to
   return the current API version ( 1.0.0 ) in its response payload.
   If specified, the client checks the x-guildpass-api-version response
3. SDK Compatibility Check: Updated GuildPassClientOptions in
   packages/sdk-lite/src/index.ts to accept an optional expectedApiVersion .
   If specified, the client checks the x-guildpass-api-version response
   header and triggers a warning when there is a version mismatch, helping
   integrations identify breaking changes.
4. Documentation: Added a new "API Versioning & Compatibility" section in
   the README.md to outline the strict compatibility contract for the
   existing /v1 routes and provide explicit guidance on how deprecations
   will be handled in the future.
5. Testing: Created a new suite of integration tests at apps/access-
   api/test/version.test.ts to verify that the version header is injected
   properly across health endpoints, business routes, and tests that the
   deprecation header is properly surfaced.
6. Workspace Fixes: Along the way, I resolved several preexisting
   TypeScript and Prisma compilation issues in the MVP (like an unclosed
   Prisma model schema block, improperly configured tsconfig.json
   configurations in test environments, and an unresolved Badge type) which
   were preventing the test suites from cleanly running.

closes #58