docs(openspec): plan wave 5, the store directory

Planning only: proposal, delta specs, design and tasks for replacing the
store surfaces. No code yet.

The batch adds a public shop read (profile + products) so the store directory,
store home and product-page store card stop reading MOCK_STORES, and so the
cart, payment and order surfaces can name a shop instead of printing "Shop".

Decisions recorded in the design:

- a `shop_profiles` table beside `shops`, so the existing admin and
  shop-admin contracts are untouched
- the four store scores stay stored profile values, because there is no review
  model and deriving them would dress fabricated numbers as computed ones
- `distanceKm` is dropped rather than faked: there is no geo model behind it
- profiles are filled by seed-demo.mjs, since they hang off shops that script
  creates
- order surfaces resolve names from one cached shop read rather than growing a
  denormalised shop name on every order payload

openspec validate --strict passes and the change is ready to apply.

openspec/changes/replace-mock-api-wave-5/specs/store-directory/spec.md

@@ -0,0 +1,37 @@
+# Spec Delta
+
+## Purpose
+
+The buyer-facing view of a shop: its public profile — identity, contact and service copy — alongside the products it sells, so the store directory, a store's home page and the store card on a product page all read real shops.
+
+## ADDED Requirements
+
+### Requirement: Public shop directory
+`GET /api/shops` SHALL list the active shops without authentication, and `GET /api/shops/{slug}` SHALL return one shop by slug, answering 404 for an unknown slug or a suspended shop. Each entry SHALL carry the shop's id, slug, bilingual name and its profile: logo and banner URLs, company, region, bilingual address, bilingual notice and after-sale copy, and four score values. A shop with no profile row SHALL still be returned, with the profile fields absent rather than invented.
+
+#### Scenario: directory lists active shops only
+- **WHEN** a suspended shop exists alongside active ones
+- **THEN** the directory lists only the active shops
+
+#### Scenario: store home by slug
+- **WHEN** a shopper opens a shop's slug
+- **THEN** the profile and the shop's products are available, with the products filtered by that shop through the catalog API
+
+#### Scenario: unknown slug is a 404
+- **WHEN** a shopper opens a slug that does not exist
+- **THEN** the API answers 404 rather than an empty profile
+
+### Requirement: Shop profile management
+A platform admin SHALL set a shop's profile with `PUT /api/admin/shops/{id}/profile`, which upserts the profile row and returns the composed shop. Bilingual fields SHALL carry non-empty `en` and `zh` text, and the write SHALL require the `platform_admin` role.
+
+#### Scenario: profile upsert round-trips
+- **WHEN** an admin sets a profile and then reads the shop publicly
+- **THEN** the public read returns those values
+
+#### Scenario: incomplete bilingual text is refused
+- **WHEN** an admin submits a notice with only `en` text
+- **THEN** the request is refused and the stored profile is unchanged
+
+#### Scenario: only platform admins may write
+- **WHEN** a shop owner or customer submits a profile
+- **THEN** the API refuses the write