Fix math, citation, and receipt scanning status in vs-flipp article

- Correct unit price increase from 13.8% to 16.1%: (18/15.5 - 1 = 16.1%)
  13.8% was the size reduction, not the unit price increase
- Remove fabricated USDA FoodData Central citation; USDA FDC is a
  nutrient database and does not produce shrinkflation cost estimates
- Remove unsupported $80-120/year claim (no verifiable source)
- Change "Receipt scanning: In development" to "Planned" — receipt
  ingestion is P3/someday-maybe, not actively in development
- Add YAML frontmatter to match blog article conventions
- Remove USDA FoodData Central from methodology citations

Addresses CTO and CEO review feedback on PR #36.

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

content/marketing/blog/cartsnitch-vs-flipp.md

@@ -1,3 +1,14 @@
+---
+title: "CartSnitch vs Flipp: Which App Actually Helps You Save More on Groceries?"
+slug: cartsnitch-vs-flipp
+status: draft
+version: 1.1
+last_updated: 2026-03-22
+description: "Flipp shows you this week's sale prices. CartSnitch tracks unit prices over time and catches shrinkflation before you notice. Here's when each tool wins."
+tags: ["comparison", "flipp", "unit-price", "shrinkflation", "smart-shopping"]
+target_publish: "2026-05"
+---
+
 # CartSnitch vs Flipp: Which App Actually Helps You Save More on Groceries?
 
 Both CartSnitch and Flipp help you find deals on groceries, but they work differently. Here is how they compare on the features that matter most for saving money.
@@ -19,15 +30,15 @@ CartSnitch is a grocery price tracking and shrinkflation detection app. It monit
 | **Unit price normalization** | ✅ Compares price-per-oz or price-per-unit across brands and stores | ❌ Compares only advertised sale prices |
 | **Store comparison** | ✅ Compares total basket cost across stores | ❌ Single-store flyer browsing |
 | **Price alerts** | ✅ Alerts on products you track | ❌ No personalized tracking |
-| **Receipt scanning** | In development | ❌ No |
+| **Receipt scanning** | Planned | ❌ No |
 
 ## The Core Difference: Unit Price vs Sale Price
 
 Flipp shows you where items are on sale this week. CartSnitch shows you when brands are quietly shrinking products or when stores are charging more than competitors — even if neither is "on sale."
 
-**Example:** A cereal brand reduces its box from 18 oz to 15.5 oz. The shelf price stays the same. Flipp shows no deal. CartSnitch flags it as a 13.8% unit price increase.
+**Example:** A cereal brand reduces its box from 18 oz to 15.5 oz. The shelf price stays the same. Flipp shows no deal. CartSnitch flags it as a 16.1% unit price increase.
 
-This is shrinkflation — and it costs the average family an estimated $80–120 per year on cereals alone, according to USDA FoodData Central analysis.
+This is shrinkflation. A shopper buying the same cereal box at the same shelf price is now paying 16.1% more per ounce — without any price tag ever changing.
 
 ## Which App Saves You More?
 
@@ -39,4 +50,4 @@ Many users end up using both — Flipp for browsing weekly deals, CartSnitch for
 
 ## Methodology
 
-CartSnitch tracks unit prices (price ÷ size) across product categories using manufacturer and retailer data. Shrinkflation percentage calculated as: `(new_price/new_size) / (old_price/old_size) - 1`. Comparisons are based on publicly available manufacturer packaging data and USDA FoodData Central.
+CartSnitch tracks unit prices (price ÷ size) across product categories using manufacturer and retailer data. Shrinkflation percentage calculated as: `(new_price/new_size) / (old_price/old_size) - 1`. Comparisons are based on publicly available manufacturer packaging data.