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/cli.ts

@@ -0,0 +1,21 @@
+#!/usr/bin/env bun
+import { migrate } from "./commands/migrate";
+import { generate } from "./commands/generate";
+import { validate } from "./commands/validate";
+
+const [cmd] = process.argv.slice(2);
+
+switch (cmd) {
+  case "migrate":
+    await migrate();
+    break;
+  case "generate":
+    await generate();
+    break;
+  case "validate":
+    await validate();
+    break;
+  default:
+    console.error(`Unknown command: ${cmd ?? "(none)"}\nUsage: loc <migrate|generate|validate>`);
+    process.exit(1);
+}