Add launch marketing content pages for April 24 beta

Publishes 9 pre-approved content pages for the CartSnitch beta launch:
- about.md — mission, team, product overview
- methodology.md — how we calculate shrinkflation
- how-it-works.md — product explainer for /how-it-works
- stores.md — supported stores (Kroger, Safeway) + coming soon
- privacy.md — data privacy and what we access/store/never do
- press-kit.md — media kit for journalists and partners
- app-store-listing.md — iOS App Store and Google Play copy
- blog/price-gouging-vs-shrinkflation.md — SEO explainer
- social/launch-day-posts.md — Twitter/X and Reddit launch posts

Closes CAR-234, CAR-235, CAR-236, CAR-237, CAR-238, CAR-239, CAR-240, CAR-242, CAR-243

Co-Authored-By: Paperclip <noreply@paperclip.ing>

content/marketing/how-it-works.md

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+# How CartSnitch Works
+
+## The Core Idea
+
+Every product at the grocery store has two prices:
+- **Shelf price** — what you pay at checkout
+- **Unit price** — what you pay per ounce, per gram, per sheet, per load
+
+Most people compare shelf prices. Smart shoppers compare unit prices.
+
+CartSnitch tracks unit prices automatically — so you don't have to do the math yourself.
+
+---
+
+## How We Track Prices
+
+CartSnitch pulls pricing data from:
+- **Store loyalty programs** — Kroger, Safeway (and more coming) — when you connect your account
+- **Public manufacturer data** — packaging changes, suggested retail prices
+- **USDA FoodData Central** — reference data for nutrition and package sizing
+
+We calculate unit price for every product we track:
+
+`Unit Price = Shelf Price ÷ Package Size`
+
+When a brand reduces package size — or a store changes its price — we catch it.
+
+---
+
+## What Is Shrinkflation Detection?
+
+Shrinkflation happens when a brand reduces the size of a product without lowering the price. The shelf price stays the same. The unit price goes up.
+
+**Example:**
+- 2021: Cereal at $4.99 for 18 oz → $0.277 per oz
+- 2024: Same cereal at $4.99 for 15.5 oz → $0.322 per oz
+
+Same price. 16% more per ounce. That's shrinkflation.
+
+CartSnitch monitors unit prices over time. When we detect a statistically significant unit price increase — whether from a size reduction, a price increase, or both — we flag it.
+
+---
+
+## How Price Alerts Work
+
+1. **You add a product** — Search for any product you buy regularly and add it to your tracked list.
+2. **We monitor unit prices** — Every time we detect a price or size change, we recalculate the unit price.
+3. **You get an alert** — If the unit price increases beyond a threshold, we notify you — so you can decide whether to switch products, switch stores, or just be aware.
+
+You choose what counts as significant. Some users set alerts for any change. Others only want to know about large unit price jumps.
+
+---
+
+## Store Comparison
+
+CartSnitch compares your total grocery basket across stores.
+
+When you connect your store accounts, we can see what you bought and where. We calculate the total cost of your typical basket at each store we support — so you know where you're getting the best overall deal.
+
+This is different from just comparing the price of one item. Some stores are cheaper on produce, others on pantry staples. CartSnitch shows you the full picture.
+
+---
+
+## What We Don't Do
+
+- **We don't collect receipts** (yet) — Store account connections give us enough data to track prices and compare baskets
+- **We don't have every product** — Beta is limited to supported stores and categories. We're adding more every week.
+- **We don't affect shelf prices** — We show you the data. What you do with it is up to you.
+
+---
+
+## How We Protect Your Data
+
+- We read price data from your connected store accounts — we never see your login credentials
+- We store only the minimum data needed to calculate unit prices and compare baskets
+- We don't sell your data to third parties
+- You can disconnect your store account at any time and delete your data
+
+---
+
+## Ready to Start?
+
+[Sign up for beta →]