feat(ios): background sync, Cmd+F search focus, scene-restored search text, regex literal highlighter

[datlechin]

Summary

Bundle of four small iOS polish items from the audit backlog. Each one stands alone; bundling because total LOC is small and review surfaces are independent.

D. Background sync via BGAppRefreshTask

• TableProMobileApp declares static let backgroundSyncIdentifier = "com.TablePro.sync" and uses .backgroundTask(.appRefresh(_:)) (iOS 17 SwiftUI native API) to register the sync handler
• On .background scenePhase, schedule the next BGAppRefreshTaskRequest with earliestBeginDate = +30min. iOS picks the actual fire time based on usage and battery
• The handler reschedules first (so the loop continues) then runs syncCoordinator.sync(...) if AppPreferences.isCloudSyncEnabled
• Logged via os.Logger("com.TablePro", "BackgroundSync")
• Info.plist gains UIBackgroundModes (fetch, processing) and BGTaskSchedulerPermittedIdentifiers array

E. Cmd+F focuses search

• DataBrowserView and TableListView add @FocusState searchFocused: Bool, apply .searchFocused($searchFocused) on the searchable, and place a hidden Cmd+F button in .background that sets searchFocused = true
• iPad with external keyboard: Cmd+F snaps focus to the search field (canonical macOS-style)

C. State restoration via @SceneStorage

• searchText in DataBrowserView and TableListView switches from @State to @SceneStorage("dataBrowser.searchText") and @SceneStorage("tableList.searchText")
• Survives process kill; per-scene on iPad multi-window
• Tradeoff: cross-table search text persists within a scene (key is not table-scoped). User clearing or retyping is the natural reset; full table-scoping needs explicit init plumbing not worth the complexity here

F. SQL syntax highlighter Regex literals

• 4 static patterns (number, line comment, block comment, string) become Regex<Substring> literals (#/.../#) — compile-time validated, no try!
• 2 dynamic patterns (keyword and function lists built from arrays) keep the runtime-built pattern but typed as Regex<Substring> via Regex(_:as:) instead of NSRegularExpression
• 6 repeated enumerateMatches blocks consolidate into a single apply(_ regex:color:scanText:in:on:protected:recordsProtection:) generic helper. The helper takes any Regex<Output> so static and dynamic patterns share one code path
• Bridges Swift Range<String.Index> to NSRange once via NSRange(_:in:) for NSTextStorage.addAttribute

Test plan

• Open the SQL editor, type a query with comments, strings, keywords, functions, numbers - colors match before/after this PR
• Type a long block comment with embedded keywords - keyword inside comment stays gray (protected range logic works)
• iPad with keyboard: in Tables list, press Cmd+F - search field gains focus and the keyboard appears. Same in Data Browser
• Type "users" in Data Browser search, force-quit the app from Recents, relaunch - search field still shows "users"
• Settings -> iCloud Sync off -> background the app -> wait 30+ minutes (or trigger via Xcode e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"com.TablePro.sync"]) - sync handler runs but exits early because of the gate
• Settings -> iCloud Sync on -> same trigger - sync runs, log shows "Background sync starting" then "Background sync completed"