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/package.json

@@ -0,0 +1,18 @@
+{
+  "name": "vnidrop-localization",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "description": "Single-source localization for VniDrop: strings.json -> .xcstrings (Apple) + per-language strings.xml (KMP/Compose).",
+  "bin": {
+    "loc": "./src/cli.ts"
+  },
+  "scripts": {
+    "migrate": "bun run src/cli.ts migrate",
+    "generate": "bun run src/cli.ts generate",
+    "validate": "bun run src/cli.ts validate"
+  },
+  "devDependencies": {
+    "bun-types": "^1.3.14"
+  }
+}