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/.gitignore

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+
+# fastlane transient run artifact
+fastlane/report.xml

iosApp/fastlane/Appfile

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+app_identifier("com.myhoneydue.honeyDue")
+team_id("X86BR9WTLD")

iosApp/fastlane/Fastfile

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+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

iosApp/fastlane/README.md

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+fastlane documentation
+----
+
+# Installation
+
+Make sure you have the latest version of the Xcode command line tools installed:
+
+```sh
+xcode-select --install
+```
+
+For _fastlane_ installation instructions, see [Installing _fastlane_](https://docs.fastlane.tools/#installing-fastlane)
+
+# Available Actions
+
+## iOS
+
+### ios upload_only
+
+```sh
+[bundle exec] fastlane ios upload_only
+```
+
+Upload an already-exported IPA to TestFlight
+
+----
+
+This README.md is auto-generated and will be re-generated every time [_fastlane_](https://fastlane.tools) is run.
+
+More information about _fastlane_ can be found on [fastlane.tools](https://fastlane.tools).
+
+The documentation of _fastlane_ can be found on [docs.fastlane.tools](https://docs.fastlane.tools).