feat(amulet-drip): batch Amulet distribution CLI with UTXO selection, tx verification, and build.sbt integration

[anhlh2311]

Summary

Adds amulet-drip, a general-purpose CLI tool for batch-distributing Amulet ($CC) tokens to multiple recipients on a Canton/Splice network.

Reads a CSV of party IDs (with optional amounts), transfers Amulet from a funded internal sender party to each recipient using the Splice Token Standard v1 TransferFactory API, and writes a JSON report of the results.

Key features

• UTXO-aware holding selection — picks the smallest holding that covers each transfer, minimizing change outputs
• Transaction verification — uses submit-and-wait-for-transaction (not just completion) to parse created Amulet contracts and identify receiver vs change
• Balance pre-check — queries sender's total balance before starting, warns if insufficient
• Incremental output — writes results to file after each transfer for crash recovery
• Rich error formatting — extracts Canton error codes and HTTP response details
• Retry logic — configurable per-transfer retry count
• Flexible CSV parsing — auto-detects headers, supports party,amount / party,expected_amount / party-only formats

Architecture

• TypeScript, esbuild, pino (logging), zod (config validation), Commander.js (CLI), vitest (testing)
• Uses generated OpenAPI clients (canton-json-api-v2-openapi for Ledger API, transfer-instruction-openapi for TransferFactory)
• Follows party-allocator project structure and conventions
• 26 unit tests (config, csv-parser, holdings)
• Registered in build.sbt with npm lifecycle tasks (build, test, lint, fix)

Files

• amulet-drip/src/ — logger, config, csv-parser, holdings, amulet-transfer, index (CLI)
• amulet-drip/__tests__/ — config, csv-parser, holdings tests
• amulet-drip/README.md — architecture diagrams (Mermaid), usage guide, env var reference
• amulet-drip/TESTING.md — local dev guide with verified port reference, auth flow, troubleshooting
• build.sbt — project definition + root aggregate registration

Pull Request Checklist

Cluster Testing

• If a cluster test is required, comment /cluster_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If a hard-migration test is required (from the latest release), comment /hdm_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If a logical synchronizer upgrade test is required (from canton-3.5), comment /lsu_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.

PR Guidelines

• Include any change that might be observable by our partners or affect their deployment in the release
  notes.
• Specify fixed issues with Fixes #n, and mention issues worked on using #n
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Merge Guidelines

• Make the git commit message look sensible when squash-merging on GitHub (most likely: just copy your PR description).