feat(cmp-firebase): commonMain-first Firebase (Analytics + Crashlytics, 15 targets) + crash→GA4 delivery audit fixes - #158

Summary

Delivers cmp-firebase as a commonMain-first Firebase library (unified Analytics + Crashlytics, one in-library setup surface across all 15 KMP targets) and then hardens the crash→GA4 delivery path via a full audit. The headline is a single, all-platform GA4 crash view: native Crashlytics on the 6 GitLive targets, and a Measurement-Protocol / app_crash bridge everywhere else — so every platform lands in one GA4/BigQuery table segmentable by kmp_platform. Companion cmp-firebase-compose stays a thin commonMain analytics layer.

Changes

commonMain-first Firebase surface

• FirebaseKit.initialize() / initialize(config) — one idempotent setup call; FirebaseConfig/FirebaseOptions builder; Android auto-init via FirebaseInitProvider; FirebaseRuntime config holder.
• Analytics: AnalyticsHelper + GitLive FirebaseAnalyticsHelper (firebaseMain tier) and a free Measurement-Protocol helper (nonFirebaseMain tier), kmp_platform auto-tagging, DI factory, NoOp/Stub/Test variants.
• Crashlytics: CrashReporter + FirebaseCrashReporter (native) / LoggingCrashReporter (fallback), CrashAnalyticsBridge → app_crash GA4 mirror.
• expect/actual across jvm · android · ios ×3 · macos ×2 · tvos ×3 · linux ×2 · mingw · js · wasmJs (15 targets), via firebaseMain/nonFirebaseMain + crashlyticsFirebaseMain/crashlyticsFallbackMain flavor source sets.

Audit fixes (crash→GA4 delivery)

• MP snake_case (critical): MpRequest now emits client_id/user_id/user_properties via @SerialName — camelCase caused GA4 to 2xx-and-silently-drop every MP event (defeated the whole fallback + free-crash path). Locked by MpSerializationTest.
• Shared analytics singleton: provideAnalyticsHelper() memoizes one process-wide instance (reset on initialize(config)) so the app's DI and the crash bridge share consent + MP client_id (was a consent leak). Locked by a singleton test.
• Opt-in uncaught capture: FirebaseKit.installUncaughtHandler() — real on JVM/Android (chains existing handler → recordException(fatal=true)), safe no-op on native/js/wasm.
• Fatal not lost to debounce: app_crash MP events flush immediately instead of on the 5s debounce.
• fatal flag reachable: asCoroutineExceptionHandler(fatal) + recording(fatal) overloads (the GA4 fatal dimension was always false).
• DEBUG bridge wired: CrashReporterModule.Mode.Logging now passes an analytics sink.
• Docs/scaffold truth: corrected JVM→nonFirebase tier tables; removed phantom watchOS (orphan Platform.watchos.kt + overstated 20/21→15 target counts — a dep, cmp-network-monitor, has no watchOS targets).

API compatibility

BCV re-dumped as additive-only — the fatal variants and the LoggingCrashReporter analytics sink are added as overloads / a secondary constructor, preserving every original signature (no binary-breaking removals). apiCheck green.

Notable files

• src/commonMain/.../FirebaseKit.kt, FirebaseConfig.kt, analytics/mp/MeasurementProtocolAnalyticsHelper.kt, crashlytics/CrashAnalyticsBridge.kt, crashlytics/LoggingCrashReporter.kt
• src/commonMain/.../UncaughtHandler.kt (+ jvm/android real, native/js/wasmJs no-op actuals)
• Tests: MpSerializationTest, AnalyticsTierRoutingTest, CrashAnalyticsBridgeTest, PlatformInjectionTest, FirebaseConfigTest

Verified inline: jvm/js/wasmJs/macosArm64/android/linuxX64/metadata compile, jvmTest green, apiCheck green.

Documentation & secrets mapping

• README.md / DEVELOPMENT.md refreshed for the cleaner API: FirebaseKit.initialize(config) builder, installUncaughtHandler(), provideAnalyticsHelper() singleton, fatal-aware capture, crash→GA4 single view. Corrected all target counts to the real 15 (10 GitLive analytics + 5 MP fallback; 6 GitLive crash + 9 logging) and removed every phantom watchOS claim (cmp-network-monitor dep ships no watchOS artifact) — including residual library-source KDocs.
• docs/firebase/SETUP.md + CLAUDE_AI_SETUP.md: keys & secrets made org-global-explicit. Analytics is a single GA4 property; org-level secrets = mbs-firebase-sa + mbs-ga4-property-id; project-level per app = google-services.json / plist / app-ids / ga4-measurement-id / mp-api-secret. Added an org-vs-project → vault-alias mapping table + the automatic secrets-resolve-path.sh --emit tier resolution rule. Fixed a property-id-vs-measurement-id conflation.
• cmp-firebase (the library) needs ONLY project-level secrets; the only genuinely-sensitive one is <proj>-mp-api-secret. The org SA + property id are read-side (growth dashboard), never consumed by the library.