Apply React Native's ccache tuning to the Xcode build

The first green run cached almost nothing: 2160 of 2190 calls uncacheable,
and the 30 hits came from the CMake bootstrap rather than Xcode.

React Native ships scripts/xcode/ccache.conf for exactly this, but it only
takes effect through their ccache-clang.sh wrapper, which sets
CCACHE_CONFIGPATH to it. Moving ccache to a compiler launcher dropped the
wrapper and with it that config, leaving ccache on its defaults — under
which Xcode's -fmodules, precompiled headers, -index-store-path and
-ivfsoverlay all make a compile "too hard" to cache.

So set the same options directly. They land in the config file the ccache
action already writes, which is where the launcher's ccache reads them from,
so the previous CCACHE_DIR/MAXSIZE/COMPILERCHECK exports are now redundant
and go.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UxzZtpa5Nz3F8ACXzX7Hww

Author: claude

.github/workflows/check.yml

@@ -197,12 +197,17 @@ jobs:
         env:
           CMAKE_RN_TRIPLETS: arm64;x86_64-apple-ios-sim
           FERRIC_TARGETS: aarch64-apple-ios-sim,x86_64-apple-ios
-      # So the ccache action's config applies to the ccache Xcode launches too.
-      - name: Expose Ccache config to Xcode
+      # Mirrors React Native's scripts/xcode/ccache.conf, which only applied
+      # while ccache ran through their wrapper script (it sets CCACHE_CONFIGPATH
+      # to it) and so no longer does now that it runs as a compiler launcher.
+      # Without this sloppiness Xcode's modules, PCH and index-store flags leave
+      # ccache treating almost every compile as uncacheable.
+      - name: Tune ccache for Xcode
         run: |
-          echo "CCACHE_DIR=`ccache --get-config cache_dir`" >> $GITHUB_ENV
-          echo "CCACHE_MAXSIZE=`ccache --get-config max_size`" >> $GITHUB_ENV
-          echo "CCACHE_COMPILERCHECK=`ccache --get-config compiler_check`" >> $GITHUB_ENV
+          ccache --set-config sloppiness=clang_index_store,file_stat_matches,include_file_ctime,include_file_mtime,ivfsoverlay,pch_defines,modules,system_headers,time_macros
+          ccache --set-config file_clone=true
+          ccache --set-config depend_mode=true
+          ccache --set-config inode_cache=true
       # Must precede `pod install`: react-native-test-app embeds the resources
       # declared in app.json when generating the workspace, skipping missing
       # ones, and the app would then expect a Metro dev server at runtime.