fix(login): correctly redirect to /password when ignoreUnknownUsername is set (#11130)

Closes #11006 

# Which Problems Are Solved

This PR addresses an issue where the ignoreUnknownUsernames setting was
not being respected in certain scenarios during the login flow.
Specifically:

- When a user was found but rejected due to login settings (e.g.,
disableLoginWithEmail), the system would return a "User not found" error
instead of redirecting to the password page as dictated by
ignoreUnknownUsernames.
- When a user was not found, and the flow fell through the registration
checks (e.g., IDP redirect failed), it would also return "User not
found" without checking ignoreUnknownUsernames.

# How the Problems Are Solved

- Introduced a helper function `handleUserNotFound` in 
`apps/login/src/lib/server/loginname.ts` to centralize the logic for
checking ignoreUnknownUsernames and redirecting to the password page.
- Updated the user validation logic to call handleUserNotFound when a
user is found but rejected by policy.
- Updated the registration fallback logic to call handleUserNotFound
instead of directly returning an error.
- Added new test cases in `apps/login/src/lib/server/loginname.test.ts`
to verify the fix and ensure no regressions.

# Additional Changes

- Fixed inconsistency in translation files

---------

Co-authored-by: Livio Spring <[email protected]>

package.json

@@ -6,10 +6,15 @@
     "changeset": "changeset",
     "clean:all": "pnpm run clean && rm -rf .nx node_modules"
   },
+  "pnpm": {
+    "overrides": {
+      "csstype": "3.1.3"
+    }
+  },
   "devDependencies": {
     "@changesets/cli": "^2.29.8",
     "nx": "21.6.1",
     "sass": "^1.97.1",
     "wait-on": "^9.0.3"
   }
-}
+}