fix: drop NitroModules qualifiers in Fs2Stream.swift

[ian-wd]

Problem

iOS Release builds fail to compile ios/Fs2Stream.swift:

Fs2Stream.swift:693:59: error: 'ArrayBuffer' is not a member type of enum '__ObjC.NitroModules'
Fs2Stream.swift:682:68: error: 'Promise' is unavailable: Un-specialized class templates are not currently supported.
Fs2Stream.swift:4:7: error: type 'Fs2Stream' does not conform to protocol 'HybridFs2StreamSpec_protocol'

The RNFS2 pod compiles Swift with C++ interop. In Release (whole-module) builds, NitroModules-Swift.h is pulled into the Swift compile, and its C++ namespace NitroModules is imported as enum __ObjC.NitroModules. That shadows the Swift module of the same name, so NitroModules.Promise resolves to the unavailable C++ class template and NitroModules.ArrayBuffer does not resolve at all. Debug builds are unaffected.

Fix

Use the bare Promise / ArrayBuffer names (14 references), matching the nitrogen-generated HybridFs2StreamSpec.swift and the other Swift sources (Fs2.swift, Downloader.swift, MediaStore.swift).

Verification

Xcode 26.4.1, example app Pods:

xcodebuild -project Pods/Pods.xcodeproj -target RNFS2 -configuration Release -sdk iphonesimulator CODE_SIGNING_ALLOWED=NO build

• Before: exit 65, same errors as above
• After: BUILD SUCCEEDED, 0 errors

Also confirmed downstream on Xcode 26.5 (Release + iphoneos archive).

CI does not build iOS, so this class of failure is not caught today.