feat: shopify demo

[leggetter]

Summary

This PR introduces a brand‑new, deterministic Shopify webhooks demo built around Hookdeck, covering setup, backpressure, and logs/retry from end to end. It provisions Hookdeck connections via API, wires Shopify webhooks through Hookdeck into the Shopify app itself, and provides scripts plus documentation to make the entire flow repeatable and demo‑friendly.

What’s Included

• New Hookdeck + Shopify demo harness

  • Adds a TypeScript upsert script (scripts/01-hookdeck-upsert.ts) that:
    • Uses the Hookdeck API (with HOOKDECK_API_KEY) to create/update two connections: shopify-orders-prod-conn (HTTP destination) and shopify-orders-dev-conn (CLI destination, same source).
    • Calls shopify app env show --path ./shopify to extract SHOPIFY_API_SECRET from the Shopify CLI (no manual env wiring).
    • Validates that shopify/shopify.app.toml exists and fails with clear guidance if not (instructs to run shopify app dev first).
    • Parses and updates shopify.app.toml via @iarna/toml to inject orders/* webhook subscriptions directly into the existing file.
    • Automatically adds or updates HOOKDECK_SOURCE_URL in .env so other scripts can rely on a single, canonical value.

• Webhooks integrated into the Shopify app

  • Introduces a new React Router route: shopify/app/routes/webhooks.shopify.orders.$.tsx.
  • Handles all orders/* topics via authenticate.webhook(request), while reading the canonical topic (orders/create, etc.) from the X-Shopify-Topic header.
  • Implements realistic failure behavior for the logs/retry story:
    • For orders/create, calls sendConfirmationText(customer.phone).
    • If phone is missing, the handler throws and returns a 500, simulating a real-world “missing phone, cannot send SMS” failure you’ll later fix and then retry via Hookdeck.
  • Removes the separate Express destination server; the Shopify app is now the single webhook destination.

• Consistent webhook path and URL handling

  • Standardizes the webhook path to /webhooks/shopify/orders to emphasize a multi‑vendor pattern.
  • 01-hookdeck-upsert.ts:
    • Appends /webhooks/shopify/orders to the Hookdeck source URL when injecting webhook URIs into shopify.app.toml.
  • scripts/02-send-simulated-webhooks.ts:
    • Reads HOOKDECK_SOURCE_URL from .env and appends /webhooks/shopify/orders when sending simulated Shopify webhooks.
  • scripts/03-trigger-shopify-webhook.ts (new):
    • Uses shopify app webhook trigger to send real Shopify webhooks through Hookdeck to /webhooks/shopify/orders.
    • Accepts --topic and uses:
      • --address {HOOKDECK_SOURCE_URL}/webhooks/shopify/orders
      • --api-version 2026-01 to avoid interactive prompts.
      • --path ./shopify so the CLI finds the right app.

• Port and dev‑experience hardening

  • Pins the React Router app to port 4000:
    • Sets port = 4000 in shopify/shopify.web.toml.
    • Updates shopify/vite.config.ts to default to port 4000 and enables strictPort: true so Vite fails instead of picking a random port.
    • Updates scripts (including 01-hookdeck-upsert.sh) and docs to consistently reference port 4000.
  • Cleans up dependencies:
    • Removes Express and related types from package.json and package-lock.json.
    • Adds @iarna/toml and @types/iarna__toml for safe TOML parsing/writing.

• Documentation for a first‑time demo

  • Overhauls shopify-webhooks-at-scale/README.md to describe this as a new, end‑to‑end demo:
    • New setup flow: run shopify app dev first, then npm run upsert to configure Hookdeck and app webhooks.
    • Explains how HOOKDECK_API_KEY and HOOKDECK_SOURCE_URL are used and automatically managed.
    • Documents the three demo stories:
      • Demo 1 – Setup & configuration (Shopify + Hookdeck wiring, webhooks in shopify.app.toml).
      • Demo 2 – Backpressure (HTTP destination, rate limiting, topic filtering over orders/*).
      • Demo 3 – Logs & retry (phone‑number failure, local debugging via CLI destination, then production retries via Hookdeck).
    • Removes all references to the old template (shopify.app.toml.template) and the removed Express destination server.

Why This Matters

• Deterministic demos: Everything needed for the three Shopify + Hookdeck demos is now expressed in code and scripts, not in ad‑hoc CLI commands.
• Realistic story: The missing‑phone failure and subsequent fix mirror real production issues, making the logs/retry demo compelling.
• Single source of truth: shopify.app.toml, Hookdeck connections, and .env stay in sync via the TypeScript upsert script and well‑documented flows.