fix: migrate legacy backups missing wallet id on restore

[coreyphillips]

Summary

Stacked on #1062. Fixes the P1 raised by the Codex review there: legacy backups that predate wallet-scoped activity data fail to decode on restore because their activity, tag and pre-activity-metadata records have no wallet id, and with bitkit-core 0.4.0 those records require one. The decode throws before any repository migration can fill a default.

Approach

Before decoding a restored envelope, each Core-owned array (activities, activityTags, tagMetadata) is handed to the matching bitkit-core migration helper as raw JSON:

• migrateBackupActivitiesJson
• migrateBackupActivityTagsJson
• migrateBackupPreActivityMetadataJson

Core fills in the default wallet id for records that lack one (or have it empty) and preserves any existing non-default id such as trezor:{hash}. The app only extracts and reinserts the sub-arrays, so it never edits Core model JSON itself. The helpers are idempotent, so current backups that already carry a wallet id are unaffected.

This is the app half of synonymdev/bitkit-core#113; the migration APIs it calls shipped in bitkit-core 0.4.0.

Changes

• BackupRepo.kt: add migrateCoreOwnedBackupFields and apply it at the METADATA and ACTIVITY restore sites.
• Bump bitkit-core to 0.4.0.

Notes

• Base is feat/wallet-scoped-core-0.3.9 (feat: bump core to 0.3.9 and hw reliability #1062), which introduces the wallet-scoped restore path this builds on. Retarget to master once feat: bump core to 0.3.9 and hw reliability #1062 merges.

[greptile-apps]

Greptile Summary

This PR adds pre-decode migration for legacy Core backup data. The main changes are:

• Migrates tagMetadata before metadata restore decoding.
• Migrates activities and activityTags before activity restore decoding.
• Adds a shared helper for patching Core-owned JSON array fields.
• Bumps bitkit-core to 0.4.0 for the migration helpers.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The migrated fields match the current top-level backup payload shape.
• The restore helper preserves the surrounding JSON object and only replaces array fields after migration output parses as JSON.

Important Files Changed

Filename	Overview
app/src/main/java/to/bitkit/repositories/BackupRepo.kt	Adds restore-time migration for Core-owned backup arrays before decoding metadata and activity payloads.
gradle/libs.versions.toml	Updates bitkit-core to 0.4.0 so the restore path can call the new migration helpers.

_{Reviews (1): Last reviewed commit: "fix: migrate legacy backups missing wall..." | Re-trigger Greptile}

[piotr-iohk]

Build failure looks like a missing Maven artifact, not a code issue: Could not find com.synonym:bitkit-core-android:0.4.0.

bitkit-core Gradle Package for v0.4.0 is still running

[piotr-iohk]

tACK

• In-place upgrade 2.3.1 → head : wallet state intact, Trezor pair + TO_SPENDING worked
• 2.3.1 VSS backup → wipe → restore on head: legacy wallet restored cleanly; logs show Full restore success, Restored 3 activities, 1 activity tags; balances/channel/order came back (on-chain + spending), Trezor pair + TO_SPENDING worked
• no issues in logs

[piotr-iohk]

Merging, my latest push only resolves the libs.versions.toml conflict with master (paykit bump), with no further code changes.