Add durable Arc Receipts persistence

[horn111]

Description

Adds the first durability layer for Arc Receipts.

This update introduces persistent receipt primitives in @arc-nano-kit/sdk/receipts, plus an optional SQLite-backed store for local/dev persistence. Invoices, receipts, webhook events, webhook deliveries, and watcher cursors can now survive process restart while keeping the existing in-memory APIs backwards-compatible.

Type of Change

• New feature (non-breaking change which adds functionality)
• Documentation update
• Refactoring (no functional changes)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change

Key Changes

• Added ReceiptStore, InMemoryReceiptStore, PersistentReceiptLedger, and PersistentWebhookInbox.
• Added JSON-safe serialization for bigint fields such as blockNumber.
• Added optional @arc-nano-kit/sqlite package with SqliteReceiptStore.
• Added persistent watcher cursor support so polling can resume after restart.
• Added persistent webhook delivery replay with attempt counts stored across restarts.
• Added a framework-light signed webhook route helper for Web Request / Next.js route handlers.
• Updated the demo to support ARC_RECEIPTS_STORE=sqlite locally while keeping hosted/Vercel demo in-memory by default.
• Added persistence docs and updated README, ROADMAP, SDK docs, architecture docs, receipts docs, demo script, and changelog.

Verification

• npm.cmd run typecheck
• npm.cmd run build --workspace=packages/sdk
• npm.cmd run build --workspace=packages/sqlite
• npm.cmd run test --workspaces --if-present -- --reporter=dot
• node_modules\.bin\tsc.cmd --noEmit --project apps/demo/tsconfig.json --incremental false
• npm.cmd run build --workspace=apps/demo
• git diff --check

Notes

SQLite is optional and intended for local/dev persistence in this release. Postgres and hosted persistence remain planned follow-up work.

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Project	Deployment	Actions	Updated (UTC)
arc-nano-kit-demo	Ready	Preview, Comment	Jul 8, 2026 5:10pm