docs(android-sdk): document App Links support for the redirect URI

[xiaoyijun]

Summary

Make App Links an officially supported redirect option, ahead of the v3 release. The SDK runtime is already scheme-agnostic (isValidRedirectUri and the callback URI matching accept https redirect URIs as-is), so this is a documentation/contract change only — no behavior change.

• README: new "Use App Links instead of a custom scheme" section covering the full integration path: hosting assetlinks.json (including the Play App Signing fingerprint pitfall), declaring the autoVerify intent filter on the SDK's receiver activity via manifest merging, console registration, the fallback-page responsibility, and verification via adb shell pm get-app-links. Apps that do not use the custom scheme can drop the SDK's built-in filter with <intent-filter tools:node="removeAll" />, which also lifts the logtoRedirectScheme placeholder requirement (manifest merging processes tools:node before placeholder substitution; verified against AGP 7.1.2).
• Contract: the fully qualified name of LogtoRedirectReceiverActivity is now documented as public API (apps reference it from their manifests), so renaming or moving it becomes a breaking change. Noted in its KDoc and in the SDK manifest comment.
• KDoc fix: signOut claimed the post sign-out redirect URI's scheme "must match the logtoRedirectScheme manifest placeholder", which is not true for App Links; reworded to be scheme-neutral.

Testing

Tested locally: built the sample app without defining logtoRedirectScheme and with an App Links filter declared (both tools:node="replace" and <intent-filter tools:node="removeAll" /> variants) and inspected the merged manifest — the SDK's attributes are inherited, the custom-scheme filter is removed, and the https filter with autoVerify is in place.

Checklist

• .changeset
• unit tests
• integration tests
• necessary TSDoc comments

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the Android SDK’s public integration contract and documentation to explicitly support using Android App Links (https) as redirect URIs (in addition to custom schemes), without changing runtime behavior.

Changes:

• Document App Links as an officially supported redirect option in the root README, including manifest-merging instructions and verification guidance.
• Update signOut KDoc to be scheme-neutral and align it with App Links support.
• Document LogtoRedirectReceiverActivity’s fully qualified name as public API (manifest-referenced) in both KDoc and the SDK manifest comments.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
README.md	Adds an App Links integration section describing assetlinks.json, intent filters, console registration, and verification.
android-sdk/android/src/main/kotlin/io/logto/sdk/android/LogtoClient.kt	Rewords signOut KDoc to remove the custom-scheme-only requirement.
android-sdk/android/src/main/kotlin/io/logto/sdk/android/auth/logto/LogtoRedirectReceiverActivity.kt	Notes the activity FQN is public API for manifest merging / App Links integration.
android-sdk/android/src/main/AndroidManifest.xml	Documents that apps may add App Links intent filters (or remove the built-in filter) via manifest merging.

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