Drop articles before renameable domain words

[dadachi]

Summary

• Apply SUBSTRATE-CONTRACT.md rule 1: UI strings must not couple articles to renameable domain nouns (Shop, ItemTag, Shopkeeper), so the agent's rename pipeline produces grammatical output for any target word (e.g. "Swipe an item tag…" → "Swipe an patient…" after ItemTag → Patient).
• Mirrors nativeapptemplate/NativeAppTemplate-iOS#77. Of the 7 iOS UI string changes, 3 have Android equivalents in app/src/main/res/values/strings.xml; the other 4 are toast/error strings (shopDeletedError, itemTagDeletedError, itemTagCompletedError, itemTagIdledError) that don't exist on Android, so they're skipped.
• The 1 iOS test-fixture change (ShopAdapterTest.swift) maps to the seed JSON in app/src/main/assets/{shop,shops}.json plus the matching DemoShopRepositoryTest assertions — all four "This is a Shop1"-style strings updated to "This is Shop1" so demo deserialization tests stay green.
• One change matches the contract's "Also good" example verbatim: shop_detail_instruction becomes "Swipe to change item tag status."

Test plan

• ./gradlew testDebugUnitTest --tests "com.nativeapptemplate.nativeapptemplatefree.demo.shop.DemoShopRepositoryTest" — passes
• ./gradlew spotlessCheck lintDebug — clean
• Spot-check the affected UI strings render correctly: shop list empty state ("Tap shop below"), item-tag list empty state ("Add a new item tag and start changing item tag status."), shop detail instruction ("Swipe to change item tag status.")

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