refactor(auth): unify use-case I/O schemas + presenter + feature error map

Per Plan 9 (spec R1-R28):
- Use cases: input + output schemas (signIn, signUp); input-only for
  signOut (void output). Use case body validates output via
  outputSchema.parse before returning.
- Controllers: receive `unknown`; safeParse with the use-case schema;
  presenter (returning cookie) for signIn/signUp; void return for
  signOut.
- New integrations/api/procedures.ts with authProcedure built via
  defineErrorMiddleware([[InputParseError,"BAD_REQUEST"],
  [AuthenticationError,"UNAUTHORIZED"], [UnauthenticatedError,
  "UNAUTHORIZED"], [UnauthorizedError,"FORBIDDEN"]]).
- Router uses authProcedure + .input(xInputSchema) for every procedure.
- src/index.ts exports schemas + types + IUseCase/IController aliases.
- package.json gains ./ui subpath; src/ui/index.ts placeholder
  (auth has no query builders today).
- New tests: R25 output-validation per use case (signIn, signUp);
  R26 router error-mapping (UNAUTHORIZED on missing user,
  BAD_REQUEST on schema fail).

Refactor log: §1, §2, §3.1, §3.2, §3.3, §5.1, §5.2, §6.1, §6.2
Spec: R1–R6, R8–R15, R18, R19, R22–R26

packages/auth/src/index.ts

@@ -9,3 +9,29 @@ export {
 } from "./entities/errors/auth";
 export { InputParseError } from "./entities/errors/common";
 export { SESSION_COOKIE } from "./config";
+
+// Use case schemas + types (Plan 9 R18)
+export {
+  signInInputSchema,
+  signInOutputSchema,
+  type SignInInput,
+  type SignInOutput,
+  type ISignInUseCase,
+} from "./application/use-cases/sign-in.use-case";
+export {
+  signUpInputSchema,
+  signUpOutputSchema,
+  type SignUpInput,
+  type SignUpOutput,
+  type ISignUpUseCase,
+} from "./application/use-cases/sign-up.use-case";
+export {
+  signOutInputSchema,
+  type SignOutInput,
+  type ISignOutUseCase,
+} from "./application/use-cases/sign-out.use-case";
+
+// Controller type aliases
+export type { ISignInController } from "./interface-adapters/controllers/sign-in.controller";
+export type { ISignUpController } from "./interface-adapters/controllers/sign-up.controller";
+export type { ISignOutController } from "./interface-adapters/controllers/sign-out.controller";