iOS: add fastlane config for TestFlight upload

Adds fastlane Appfile/Fastfile (upload_only lane that pushes an already-
exported IPA to TestFlight via the ASC API key) and the generated README.
The ASC .p8 private key stays outside the repo (~/.appstoreconnect); only
its key_id/issuer_id identifiers are referenced. Gitignores the transient
fastlane/report.xml run artifact.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

iosApp/fastlane/Fastfile

@@ -0,0 +1,18 @@
+default_platform(:ios)
+
+platform :ios do
+  desc "Upload an already-exported IPA to TestFlight"
+  lane :upload_only do
+    api_key = app_store_connect_api_key(
+      key_id: "H67SQ2QB98",
+      issuer_id: "c1e3de74-20ca-4e4e-8ab4-528c497ac155",
+      key_filepath: File.expand_path("~/.appstoreconnect/private_keys/AuthKey_H67SQ2QB98.p8")
+    )
+    upload_to_testflight(
+      api_key: api_key,
+      ipa: "/tmp/honeydue_export/honeyDue.ipa",
+      skip_waiting_for_build_processing: true,
+      skip_submission: true
+    )
+  end
+end