build(apple): stop tracking generated localization outputs

Localizable.xcstrings and Generated/L10n.swift are generated from
localization/strings.json — the single source of truth — yet were committed,
which caused redundant tracking and a spurious ~10k-line diff every time
Xcode reformatted the catalog on build.

Treat them like the (already gitignored) Rust bindings: generate at build
time instead of tracking them. gitignore both; make the `apple-project`
target depend on `localization` so `bun run generate` recreates them before
xcodegen; install Bun in the Apple CI job and trigger it on localization/**.
Android strings.xml stays tracked — it has no reformatting churn and its
build doesn't run the generator.

.github/workflows/apple.yml

@@ -12,6 +12,7 @@ on:
       - "config.mk"
       - "make/**"
       - ".github/workflows/apple.yml"
+      - "localization/**"
   push:
     branches:
       - master
@@ -25,6 +26,7 @@ on:
       - "config.mk"
       - "make/**"
       - ".github/workflows/apple.yml"
+      - "localization/**"
 
 permissions:
   contents: read
@@ -63,5 +65,10 @@ jobs:
       - name: Install XcodeGen
         run: brew install xcodegen
 
+      - name: Install Bun
+        # The Apple l10n catalog (Localizable.xcstrings) and L10n.swift are
+        # generated from localization/strings.json at build time, not tracked.
+        uses: oven-sh/setup-bun@v2
+
       - name: Build and test Apple app
         run: make check-apple