[russellwheatley]

Bumps Firebase iOS SDK 12.18.0 → 12.19.3 for v26, the last major with CocoaPods support. 12.19.3 removes root certs for compromised eMudhra intermediate CAs from the embedded trust store (Cloud Firestore security update, release notes). v26 counterpart of #9391 (v27, SDK 13.1.1).

• sdkVersions.ios.firebase → 12.19.3 (SPM minimum), docs/index.mdx examples and the test-rn-bare Xcode pin updated
• CocoaPods: 12.19.3 is only published for Firebase, FirebaseCore and FirebaseFirestore. Every other pod stops at 12.19.0, so the exact pins in the podspecs (e.g. FirebaseAnalytics/Core, FirebaseCoreExtension) could not resolve. When the default version is used, the podspecs now declare ~> 12.19.0 instead, so each pod resolves to its newest patch. A version pinned via $FirebaseSDKVersion / FIREBASE_SDK_VERSION stays exact.
• test_expo_ios_link and test_rn_bare_ios_build now also run on packages/app/package.json changes, so SDK bumps on this branch exercise them (main already does this)

No 12.18.x patch exists and 12.19.1 / 12.19.2 aren't on CocoaPods trunk, so this crosses a minor. 12.19.0 adds the GeminiLanguageModel public preview plus some Auth and App Check build/crash fixes.

Targets release-v26, cut from v26.4.0.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.54%. Comparing base (06701af) to head (a1b135a).

Additional details and impacted files

@@                Coverage Diff                @@
##             release-v26    #9393      +/-   ##
=================================================
+ Coverage          69.09%   69.54%   +0.45%     
  Complexity          2129     2129              
=================================================
  Files                442      444       +2     
  Lines              25187    25558     +371     
  Branches            4260     4260              
=================================================
+ Hits               17400    17771     +371     
  Misses              6379     6379              
  Partials            1408     1408              

Flag	Coverage Δ
android-native	65.92% <ø> (ø)
e2e-ts-android	54.11% <ø> (ø)
e2e-ts-ios	53.63% <ø> (ø)
e2e-ts-macos	49.86% <ø> (ø)
ios-ruby	100.00% <100.00%> (?)
jest	47.72% <ø> (ø)

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[mikehardy]

there were issues before with using ~> for cocoapods as dependencies would slip forward and sometimes cause incompatibility, which is why we pinned them

However, cocoapods will only ever publish fixes that we really really want since it's in maintenance mode, so letting dependencies slip within a semver fix band now seems appropriate.