feat: add iOS Safari web extension flow

[2001Y]

Summary

• add the iOS Safari Web Extension target, native bridge, and shared Safari request/response pipeline
• implement generated-password follow-up handling, setup progress UX, and action-panel driven save/update flows
• stabilize simulator action-extension runtime enough to run credentialed Safari live QA end-to-end
• add dedicated Safari Web Extension tests, fixture pages, and simulator-driven live QA coverage

Motivation

• enable Bitwarden's iOS Safari Web Extension flow end-to-end in the iOS app and shared runtime
• bring setup UX, page-action handling, and native/web bridge behavior to a shippable state
• replace the last manual-only Safari validation gap with reproducible simulator coverage

Changes

• add BitwardenSafariWebExtension target scaffold, manifest resources, and native handler/bridge wiring
• add shared Safari extension request/response/suggestion/submission models and bridge codec coverage
• implement generated-password follow-up context, native request context propagation, and save/update persistence flows
• derive action-extension save-login and change-password routes directly from collected pageDetails
• add simulator-safe persisted store fallbacks for app-extension Core Data paths
• suppress non-actionable simulator .appex error assertions/noise that blocked live QA
• add local Safari fixture pages for login, signup, and change-password flows
• add a dedicated BitwardenUITests target/scheme plus fixture-driven simulator smoke coverage
• document the fixture-based Safari testing loop and add lightweight Maestro smoke flows

Test Plan

• node BitwardenSafariWebExtension/Application/Support/content.node-test.js
• node BitwardenSafariWebExtension/Application/Support/background.node-test.js
• xcodebuild test -disableAutomaticPackageResolution -project Bitwarden.xcodeproj -scheme Bitwarden -destination 'platform=iOS Simulator,name=iPhone 17 Pro,OS=26.4.1' -only-testing:BitwardenSafariWebExtensionTests -only-testing:BitwardenSharedTests/SafariExtensionRequestProcessorTests -only-testing:BitwardenSharedTests/SafariExtensionResponseTests -only-testing:BitwardenSharedTests/SafariExtensionBridgeCodecTests -only-testing:BitwardenSharedTests/SafariExtensionStateTests -only-testing:BitwardenSharedTests/SafariExtensionProcessorTests -only-testing:BitwardenSharedTests/SettingsCoordinatorTests -only-testing:BitwardenSharedViewInspectorTests/SafariExtensionViewTests CODE_SIGNING_ALLOWED=NO COMPILER_INDEX_STORE_ENABLE=NO
• xcodebuild build -disableAutomaticPackageResolution -project Bitwarden.xcodeproj -scheme BitwardenSafariWebExtension -destination 'generic/platform=iOS Simulator' CODE_SIGNING_ALLOWED=NO COMPILER_INDEX_STORE_ENABLE=NO
• xcodebuild test -project Bitwarden.xcodeproj -scheme Bitwarden -destination 'platform=iOS Simulator,name=iPhone 17 Pro,OS=26.4.1' -only-testing:BitwardenSharedTests/ActionExtensionHelperTests -only-testing:BitwardenSharedTests/DataStoreTests -only-testing:BitwardenKitTests/ErrorNetworkingTests COMPILER_INDEX_STORE_ENABLE=NO
• signed simulator build launches Bitwarden to the onboarding screen on iPhone 17 Pro (iOS 26.4.1)
• fresh-app direct self-hosted login reaches LoginMasterPasswordEntry with password.2001y.dev
• simulator Safari live flow saves a new login from Docs/safari-extension-dev-fixtures/signup.html
• simulator Safari live flow opens generator from signup and returns to New login follow-up
• simulator Safari live flow fills saved credentials into Docs/safari-extension-dev-fixtures/login.html
• simulator Safari live flow reaches matched-item selection / password actions from Docs/safari-extension-dev-fixtures/change-password.html

Screenshots / Examples

• N/A

Notes for Reviewers

• the branch now includes reproducible local fixtures and a dedicated UITest target for Safari validation instead of leaving credentialed live QA as an untracked manual step
• simulator action-extension stabilization here is intentionally scoped to development/live-QA reliability (.appex Core Data fallback + non-loggable assertion suppression), not a product-facing entitlement change
• current upstream checks on the PR still require normal maintainer-side review / label / CLA flow

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[bitwarden-bot]

Thank you for your contribution! We've added this to our internal Community PR board for review.
ID: PM-36081
Link: https://bitwarden.atlassian.net/browse/PM-36081

Details on our contribution process can be found here: https://contributing.bitwarden.com/contributing/pull-requests/community-pr-process.

[2001Y]

Follow-up QA note:

• Automated coverage is green for the Safari Web Extension stack (JS node tests, shared Safari tests, dedicated bridge/handler tests, appex build).
• Signed simulator builds also launch the Bitwarden app successfully; I verified the app reaches the onboarding screen on iPhone 17 Pro / iOS 26.4.1.
• The remaining gap is login-gated live QA for the Safari flows themselves (fill, save, change password, generate password, generated-password follow-up) because that requires a usable Bitwarden account/session inside the simulator.
• Keeping this PR in draft until that credentialed manual pass is completed is probably the safest path.