fix(mastodon): preserve paging type under R8

[Tlaster]

Summary

• Mark MastodonPaging<T> with @Serializable.
• Reuse kotlinx serialization's consumer keep rule to retain the model's generic Signature in R8 full mode.

Root cause

Ktorfit reads the response element type from MastodonPaging<T> at runtime. R8 removed that generic signature, leaving TypeData.typeArgs empty and causing NoSuchElementException: List is empty in the Mastodon converter.

Verification

• ./gradlew :social:mastodon:jvmTest --console=plain
• ./gradlew :app:assembleRelease --console=plain
• Inspected the release DEX and confirmed MastodonPaging<T> retains dalvik.annotation.Signature.
• Installed the release APK on the emulator and confirmed the Mastodon timeline loads without the previous error.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-04T10:55:04.351191Z	9e2517c	PR opened

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