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/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "types": ["bun-types"],
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "skipLibCheck": true,
+    "verbatimModuleSyntax": true
+  },
+  "include": ["src"]
+}