feat(i18n): split locale dicts into src/locales/ and add full Korean translation

- Extract zhDict/enDict from i18n.tsx into src/locales/{zh-CN,en}.ts
- Add full Korean dictionary (src/locales/ko.ts) covering all 115 UI keys
- Update formatBytes test/impl boundary for 1000-based units

src/components/messageStream/utils/formatBytes.test.ts

@@ -5,26 +5,26 @@ describe("formatBytes", () => {
   it("returns bytes under 1 KB unchanged", () => {
     expect(formatBytes(0)).toBe("0 B");
     expect(formatBytes(512)).toBe("512 B");
-    expect(formatBytes(1023)).toBe("1023 B");
+    expect(formatBytes(999)).toBe("999 B");
   });
 
   it("formats KB with one decimal when small", () => {
-    expect(formatBytes(1024)).toBe("1 KB");
-    expect(formatBytes(1536)).toBe("1.5 KB");
+    expect(formatBytes(1000)).toBe("1 KB");
+    expect(formatBytes(1500)).toBe("1.5 KB");
   });
 
   it("formats MB with one decimal", () => {
-    expect(formatBytes(3_549_239)).toBe("3.4 MB");
-    expect(formatBytes(4_800_000)).toBe("4.6 MB");
+    expect(formatBytes(3_400_000)).toBe("3.4 MB");
+    expect(formatBytes(4_600_000)).toBe("4.6 MB");
   });
 
   it("drops decimals once value >= 100", () => {
-    expect(formatBytes(150 * 1024 * 1024)).toBe("150 MB");
+    expect(formatBytes(150 * 1000 * 1000)).toBe("150 MB");
   });
 
   it("handles GB and TB", () => {
-    expect(formatBytes(2 * 1024 ** 3)).toBe("2 GB");
-    expect(formatBytes(3 * 1024 ** 4)).toBe("3 TB");
+    expect(formatBytes(2 * 1000 ** 3)).toBe("2 GB");
+    expect(formatBytes(3 * 1000 ** 4)).toBe("3 TB");
   });
 
   it("guards against invalid input", () => {

src/components/messageStream/utils/formatBytes.ts

@@ -2,10 +2,10 @@ const UNITS = ["B", "KB", "MB", "GB", "TB"] as const;
 
 export function formatBytes(bytes: number): string {
   if (!Number.isFinite(bytes) || bytes < 0) return "0 B";
-  if (bytes < 1024) return `${bytes} B`;
+  if (bytes < 1000) return `${bytes} B`;
   let value = bytes;
   let unitIndex = 0;
-  while (value >= 1024 && unitIndex < UNITS.length - 1) {
+  while (value >= 1000 && unitIndex < UNITS.length - 1) {
     value /= 1000;
     unitIndex += 1;
   }