feat: end-to-end dust protection (classification, restrictions, donation, report)

[Parsh]

Summary

This PR delivers the complete dust-protection feature set for Keeper across wallet sync, coin selection, UTXO management, send flow, transaction history, and wallet settings.

It combines five related OpenSpec changes into one cohesive rollout:

• dust-utxo-classification
• dust-spend-restrictions
• dust-donation
• dust-descendant-classification
• dust-analysis-report

Problem

Dust attacks can reduce user privacy by encouraging linkage when suspicious small UTXOs are spent. Prior behavior lacked end-to-end protection and clear user actions.

What’s Included

1) Automatic dust detection + manual spendability control

• Adds UTXO spendability state and manual override support.
• Classifies suspicious dust outputs during wallet refresh.
• Preserves manual overrides across refresh/hard refresh.
• Adds user action to mark UTXO as Do Not Spend / Spendable.
• Surfaces a one-time toast when new suspicious dust is detected.

2) Spend restrictions in send flow

• Excludes Do Not Spend UTXOs from automatic coin selection.
• Uses spendable-only balance in send amount flow.
• Adds manual-selection warning modal before selecting a Do Not Spend coin.

3) Dust donation flow

• Adds contextual Donate Dust CTA in Manage Coins.
• Builds donation tx using only Do Not Spend UTXOs at low fee tier.
• Handles eligibility check and too-small-to-donate path.
• Reuses SendConfirmation in locked donation mode.

4) Address-level taint + descendant propagation

• Moves from per-UTXO-only logic to address-level tainting.
• Introduces transaction wallet-output data and hard-refresh backfill.
• Propagates taint forward through transaction graph (BFS) with manual-override chain break.
• Marks transactions as Potential dust spend when tainted senders are involved.
• Adds nuanced dust reasons for UTXOs (initial, adjacent, descendant).

5) Dust Report (wallet/vault settings)

• Adds Dust Report entry point from Wallet/Vault Settings.
• Implements phases: start, scanning, result, empty, error.
• Shows summary + sections for Active Dust, Linked Coins, and Past Dust Spends.
• Persists last-scanned timestamp in MMKV.
• Includes inline Donate Dust confirmation from report results.

Architecture / Data Changes

• Realm schema updates for UTXO spendability fields and transaction wallet outputs.
• Dust classification utility refactor to address-taint model.
• Saga updates for snapshot restore, scan-mode behavior, backfill, and tagging.
• UI updates across Home wallet card, Wallet Details/More options, UTXO screens, Send, and Dust Report.
• Localization updates (EN/ES).

Testing

Automated tests added/updated

• Dust classification logic (including descendant/address-taint scenarios).
• Donation flow eligibility and send-confirmation donation mode.
• UTXO footer Donate Dust visibility.
• Dust report derivation and screen behavior.
• UTXO spendability hook logic.

Maestro flows added

• flows/dustUTXOClassification.yaml
• flows/dustSpendRestrictions.yaml
• flows/dustDonation.yaml
• flows/dustDescendantClassification.yaml
• flows/dustAnalysisReport.yaml
• flows/dustSanity.yaml

Notes

• This PR is intentionally broad because these features are tightly coupled and designed to ship as one privacy-protection experience.
• Existing open-spec artifacts for all five changes are included for traceability and implementation parity.