Add shopping category schema

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Goal

Add a shopping category schema for apps that understand product browsing and purchase preferences.

This should help Memact convert messy shopping signals into user-readable Wiki entries without turning one-off purchases into fake identity lore.

Context examples

Shopping apps may know things like:

• preferred product categories
• disliked product categories
• preferred brands
• disliked brands
• budget range signals
• repeated purchases
• abandoned carts
• gift purchases vs personal purchases
• temporary purchase intent

Work to do

• Define useful context fields for the shopping category
• Add example raw app context dumps
• Add normalized context examples
• Add user-facing Wiki entry templates
• Mark sensitive or risky fields clearly
• Suggest category-level permissions apps should request
• Add tests for safe context shaping

Important product rule

Do not treat every purchase as a stable preference. Gifts, emergencies, shared-account purchases, and one-time needs should be modeled carefully.

Acceptance criteria

• Schema separates durable preferences from temporary purchase intent
• Raw app input examples exist
• Normalized output examples exist
• Wiki entry examples are human-readable
• Tests cover at least one valid and one misleading purchase case

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Maintainer note for SSoC26 contributors:

Please comment before starting so work does not get duplicated. Keep the first PR small and focused.

For category schemas, apps should propose context; users control what becomes accepted memory. Prefer user-readable summaries over raw personal data, avoid sensitive trait inference, and do not write fake certainty.

Before opening a PR, read MEMACT.md and make sure your schema includes examples, Wiki entry outputs, permission suggestions, and at least basic tests.