feat: add chargeback management system and granular communication pre…

[villadel]

…ferences

• Chargeback domain types with Visa/Mastercard/Amex reason code mapping
• ChargebackService: ingest, evidence auto-population, representment, analytics
• deadline_checker worker: D-3 escalation countdown
• auto_submit_worker: automated representment before deadline
• ChargebackDashboardScreen: analytics, open cases, deadline countdown, edge case flags
• CommPreferences types: per-category/per-channel opt-in with waterfall rules
• PreferenceService: granular updates, regulatory bypass, opt-out marketing
• WaterfallRouter: ordered channel delivery with fallback on failure
• CommunicationPreferencesScreen: per-category toggle UI with required-category guard
• Navigation routes wired: ChargebackDashboard, CommunicationPreferences
• .gitignore: exclude test_snapshots, debug output files, backup files

Pull Request Checklist

Quality Gates (All must pass before merge)

• Lint: Code passes ESLint and Prettier checks
• Type Check: TypeScript compilation succeeds
• Tests: All tests pass
• Build: Project builds successfully
• Rust Format: Smart contract formatting is correct
• Rust Clippy: Smart contract linting passes
• Rust Tests: All smart contract tests pass
• Rust Build: Smart contracts compile successfully

Additional Requirements

• New code has appropriate TypeScript types
• No hardcoded secrets or credentials
• New features have corresponding tests
• Documentation updated if needed

Reviewers

• At least 1 approval required for merge
• All CI checks must be green

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This PR will not be mergeable until all quality gates pass.
closes #564
closes #565

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