Phase 2A-1: Port ItemTag schema update from paid iOS

[dadachi]

Summary

Ports https://github.com/nativeapptemplate/NativeAppTemplate-iOS/pull/49 (Phase 2A-1) to the Free iOS repo.

• Updates iOS to the Rails API v2 ItemTag schema (name, description, position; removes queueNumber, scanState, customerReadAt, alreadyCompleted).
• Data layer only — NFC/QR/Scan code is kept and adapted to compile against the new schema. Full Scan/NFC deletion is Phase 2A-2, UI rewrite is 2A-3, test fixes are 2A-4.
• Stacked on top of substrate-v2; targets that branch.

Key changes

• ItemTag: queueNumber → name; added description: String, position: Int?; removed scanState/customerReadAt/alreadyCompleted. toJson() emits new keys. scanUrl() kept for 2A-2.
• ItemTagAdapter: parses name/description/position; drops legacy attrs.
• PermissionsRequest: maximum_queue_number_length meta is now optional with default 256 (full removal deferred to 2A-3).
• SessionController / App.swift null stub: maximumQueueNumberLength default 0 → 256.
• ViewModels: queueNumber → name; validateQueueNumberLength → validateNameLength; hasInvalidDataQueueNumber → hasInvalidDataName. Form bindings and footer references updated.
• Removed 5 production call sites of the deleted fields (ShowTagInfoScanResultView, ScanViewModel, ShopDetailViewModel, ShopDetailCardView, MainViewModel) — each flagged with a // TODO: removed in Phase 2A-2 marker.
• Shop drops displayShopServerPath / displayShopServerUrl; ShopDetailView loses the "Open Server Number Tags Webpage" link; ShopSettingsView loses the Section that linked to the deleted NumberTagsWebpageListView. NumberTagsWebpageListView + ViewModel + tests deleted.
• Test helpers updated to compile with the new schema. ScanViewModelTest (queue/NFC-specific) deleted ahead of 2A-2. completeTagWhenAlreadyCompleted test removed.

Test plan

• make lint passes (SwiftLint 0 violations, SwiftFormat 0 files require formatting)
• xcodebuild build — ** BUILD SUCCEEDED ** (iPhone 17, iOS 26.2)
• xcodebuild build-for-testing — ** TEST BUILD SUCCEEDED **
• Tests run green in Xcode (Cmd+U). Known failures deferred to Phase 2A-4 — do not block this PR on them.
• grep -rn "queueNumber" NativeAppTemplate/ returns 0 matches (identifier was eliminated in production code)
• grep -rn "scanState\|customerReadAt\|alreadyCompleted" NativeAppTemplate/ returns only // TODO: removed in Phase 2A-2 markers
• Manual smoke test: launch app, browse ItemTag list / detail / create / edit — no crash

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