Build a Shopify app for merchants

You are a senior Shopify app developer. Build a complete public Shopify app with me, phase by phase, that passes Shopify App Store review.

## The app
- App name: [APP NAME]
- Problem it solves for merchants: [PROBLEM]
- What it changes in the store front: [e.g. a widget on product pages, nothing]
- Pricing: [e.g. free plan + $9.99/month Pro with 7-day trial]
- Tech: Shopify's Remix app template (or tell me if you recommend otherwise)

## Features
1. App setup with Shopify CLI, OAuth install flow, session storage, and the right access scopes (only what is needed).
2. Embedded admin UI with Polaris and App Bridge: dashboard, settings, and the main feature screens with loading and empty states.
3. Theme app extension (app blocks and app embeds) for anything shown on the storefront, so merchants add it in the theme editor with no code.
4. GraphQL Admin API usage for products, orders or customers as needed, with pagination and rate-limit handling.
5. Webhooks: app/uninstalled, the mandatory GDPR webhooks (customers/data_request, customers/redact, shop/redact), and any data webhooks the feature needs, verified with HMAC.
6. Billing with the Billing API: plans, trial, upgrade, downgrade, and feature gating.
7. Onboarding checklist inside the app.
8. Analytics for the merchant (what the app did for them, e.g. revenue influenced).
9. App listing content and a pre-submission checklist.

## Shopify rules
- Use only the latest stable API version and avoid deprecated REST endpoints where GraphQL exists.
- Storefront code must not slow the store down: small script, loaded async, no layout shift.
- Clean uninstall: stop all jobs and remove storefront code when the app is uninstalled.

## Quality rules (apply to every phase)
- Security: prepared statements or an ORM for every query, output escaping, CSRF tokens on every form, passwords hashed with bcrypt or Argon2, rate-limited login, role checks on the server for every admin route, file uploads checked by type and size and stored outside the web root or with random names, secrets only in an .env file.
- Validation: validate every input on the server (and also in the browser for speed). Show clear error messages next to the field that is wrong, and keep what the user already typed.
- Performance: pagination on every list, database indexes on every column used for search, filter or join, lazy-loaded and resized images (WebP), caching for pages that rarely change, no N+1 queries.
- Responsive and accessible: mobile first, works from 360px to wide desktop, proper labels on every form field, keyboard navigation, visible focus, colour contrast of at least 4.5:1, alt text on images.
- SEO: clean URLs, a unique title and meta description per page, canonical tags, Open Graph tags, schema.org JSON-LD where it applies, an XML sitemap and robots.txt.
- Code: small functions with clear names, one responsibility per file, comments only where the reason is not obvious, consistent formatting, no dead code.
- Errors: friendly error pages (404, 500), server errors written to a log, never shown to visitors.
- Deliver with: a README (install steps, .env example, how to create the first admin), database migrations and seed data with realistic sample content, and a deployment checklist.

## How to work with me
Do not write code yet. First reply with:
1. A short summary of what you understood, and anything in the brief that is unclear or contradictory (ask me, do not guess).
2. The final tech stack, with a one-line reason for each choice.
3. The folder and file structure.
4. The full database schema: every table, column, type, index and relation.
5. Every page or screen, and every API endpoint (method, path, who can call it, what it returns).
6. The build plan as numbered phases, each one small enough to finish and test on its own.

Wait for me to reply "go". Then build one phase at a time:
- For every file, give the full path and the complete code. Never write "...", "rest of the code stays the same" or TODO.
- After each phase, tell me how to run it, what to click to test it, and what is still missing. Then wait for me to reply "next".
- If you change a file you already gave me, give the whole updated file again.