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/tests/sign-in-flow.feature.test.ts

@@ -21,21 +21,24 @@ describe("auth feature: sign-up → sign-in → sign-out", () => {
     const signUp = signUpController(signUpUseCase(users, auth));
     const signOut = signOutController(signOutUseCase(auth));
 
-    const signUpResult = await signUp({
+    // signUp returns a cookie (presenter shape)
+    const signUpCookie = await signUp({
       username: "newperson",
       password: "verysecret",
       confirmPassword: "verysecret",
     });
-    expect(signUpResult.user.username).toBe("newperson");
-    const userId = signUpResult.user.id;
+    expect(signUpCookie.name).toBe("session");
+    expect(signUpCookie.value).toBeTruthy();
 
     const signInCookie = await signIn({
       username: "newperson",
       password: "verysecret",
     });
-    expect(signInCookie.value).toBe("session_" + userId);
+    expect(signInCookie.name).toBe("session");
+    expect(signInCookie.value).toBeTruthy();
 
-    const signOutResult = await signOut(signInCookie.value);
-    expect(signOutResult.value).toBe("");
+    // signOut takes { sessionId } and returns void
+    const signOutResult = await signOut({ sessionId: signInCookie.value });
+    expect(signOutResult).toBeUndefined();
   });
 });