fix(i18n): hold every refusal reason by type, and refuse what the scan cannot read

Review round 1 of the refusal contract: it claimed more than it held.

- The other reason carriers get their Literal too (BlockedUrl, ClipError,
  FolderError, the playlist and sign-in refusal helpers), so the type
  checker refuses a reason passed by variable or an unknown literal, and
  the contract reads one shape.
- A literal reason in a detail dict built anywhere counts as a reason of
  its code; a code the scan cannot read, a refused() whose reason it
  cannot read, and a new reason passed by variable each fail the contract
  until listed with what holds them.
- A sign-in refusal key the backend no longer sends is caught too.
- localizeDetail's numbers (download cap in GB, upload cap in bytes) and
  the shared-sentence fallbacks are tested in both languages.
- One Literal parser in the contract; a stale comment fixed.

frontend/src/lib/api/refusalText.dom.test.ts

@@ -4,6 +4,7 @@
 // one case per record shape, so moving the dispatch into data changed what no reader sees.
 import { afterEach, describe, expect, it } from "vitest";
 import i18n from "../../i18n";
+import { formatBytes } from "../format";
 import { localizeDetail } from "./refusalText";
 
 afterEach(async () => {
@@ -45,6 +46,24 @@ describe.each(["en", "hu"])("localizeDetail (%s)", (lng) => {
     );
   });
 
+  it("puts a download cap in GB and an upload cap in bytes, in the reader's number format", async () => {
+    expect(await say({ code: "quota", reason: "max_bytes", limit: 1.5 * 2 ** 30 })).toContain(
+      lng === "hu" ? "1,5" : "1.5",
+    );
+    const upload = await say({ code: "upload_too_large", limit: 5_242_880 });
+    expect(upload).toContain(formatBytes(5_242_880, lng));
+    expect(upload).not.toBe(i18n.t("downloads.errors.upload.tooLarge", { size: "" }));
+  });
+
+  it("says a shared-sentence code's own fallback for a reason it does not know", async () => {
+    expect(await say({ code: "quota", reason: "nope" })).toBe(
+      i18n.t("downloads.errors.quota.generic"),
+    );
+    expect(await say({ code: "collection", reason: "nope" })).toBe(
+      i18n.t("plex.collection.editFailed"),
+    );
+  });
+
   it("says a shared-sentence code's fallback, and a fixed code's one sentence", async () => {
     expect(await say({ code: "reset", reason: "invalid" })).toBe(
       i18n.t("welcome.auth.deadLink.short"),