feat(l10n): single-source localization pipeline

Add localization/ — one strings.json is the source of truth for every
user-facing string, and a Bun CLI generates the platform files:

  loc migrate   rebuild strings.json from existing platform files (one-time)
  loc validate  structural checks (plural `other`, arg refs, coverage)
  loc generate  emit .xcstrings (Apple) + per-language strings.xml (KMP)

Canonical `{name}` placeholders are converted to each platform's positional
printf tokens using declared arg types. Plurals use CLDR categories and emit
native forms: xcstrings plural variations and Compose <plurals> blocks.

Migration folds the KMP `transfer_file_count_one`/`_other` pair into a single
plural key, so `transferFileCountResource` now returns the plural resource and
callers resolve it with pluralStringResource.

localization/src/config.ts

@@ -0,0 +1,24 @@
+import { dirname, join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+/** Repo root = parent of the localization/ directory. */
+export const REPO_ROOT = resolve(dirname(fileURLToPath(import.meta.url)), "..", "..");
+export const LOC_DIR = join(REPO_ROOT, "localization");
+export const STRINGS_JSON = join(LOC_DIR, "strings.json");
+
+/** Apple String Catalog — one file, all languages nested. */
+export const APPLE_XCSTRINGS = join(
+  REPO_ROOT,
+  "apple/VniDrop/Resources/Localizable.xcstrings",
+);
+
+/** KMP / Compose Multiplatform resources root; one values[-lang]/strings.xml per language. */
+export const KMP_RESOURCES = join(
+  REPO_ROOT,
+  "shared/src/commonMain/composeResources",
+);
+
+/** Directory holding a language's strings.xml under the compose resources root. */
+export function kmpValuesDir(lang: string, sourceLanguage: string): string {
+  return lang === sourceLanguage ? "values" : `values-${lang}`;
+}