refactor: remove all JWT-related code and references

JWT was never used - auth uses X-User-Id header. Removes jwt.ts utility,
jsonwebtoken dependency, stubbed refresh/logout endpoints, and updates
all docs (PUML diagrams, api-routes, tex, CLAUDE.md) accordingly.

apps/server/src/controllers/AuthController.ts

@@ -22,11 +22,4 @@ export class AuthController {
     }
   }
 
-  async refresh(req: Request, res: Response): Promise<void> {
-    throw new Error("Not implemented");
-  }
-
-  async logout(req: Request, res: Response): Promise<void> {
-    throw new Error("Not implemented");
-  }
 }