chore: changelogs plus header comment update (#16258)

Author: ncooke3

FirebaseAI/CHANGELOG.md

@@ -1,4 +1,6 @@
 # 12.15.0
+- [changed] Made Firebase App Check a dependency of Firebase AI Logic to
+  simplify App Check setup. (#16185)
 - [fixed] Fixed a namespace collision with the new
   `FoundationModels.LanguageModelSession.Error` type introduced in Xcode 27 Beta. (#16252)
 

FirebaseAppCheck/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 12.15.0
 - [added] Added a reCAPTCHA attestation provider. Using this provider requires the
   [reCAPTCHA Enterprise SDK to be installed](https://docs.cloud.google.com/recaptcha/docs/instrument-ios-apps#prepare-environment),
   enabling the reCAPTCHA provider on the Firebase App Check console, and

FirebaseAppCheck/Sources/DefaultProviderFactory/FIRDefaultProviderFactory.h

@@ -18,9 +18,12 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-/// The internal default provider factory that is set at +load time. It returns
-/// the Debug provider for simulator builds; otherwise, the DeviceCheck
-/// provider.
+/// The internal default provider factory that is set at +load time.
+///
+/// It returns the Debug provider for simulator builds. For device builds, it
+/// returns the reCAPTCHA provider if a reCAPTCHA site key is configured
+/// (supported on iOS and visionOS); otherwise, it returns the DeviceCheck
+/// provider (if supported).
 @interface FIRDefaultProviderFactory : NSObject <FIRAppCheckProviderFactory>
 
 @end

Firestore/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 12.15.0
 
 - [fix] Remove use of designated initializers for `forceIndex` [#16229].