refactor: rename app from Severed to OpenAppLock

Full rename ahead of App Store submission: project, targets, bundle
identifiers (dev.bchen.Severed -> dev.bchen.OpenAppLock), entitlements
file, app entry point, user-facing onboarding strings, test helpers,
and docs. Verified: all 62 unit tests pass.

OpenAppLockTests/TestSupport.swift

@@ -0,0 +1,36 @@
+//
+//  TestSupport.swift
+//  OpenAppLockTests
+//
+
+import Foundation
+
+@testable import OpenAppLock
+
+/// Fixed UTC gregorian calendar so schedule math is deterministic regardless
+/// of the machine running the tests.
+let utc: Calendar = {
+    var calendar = Calendar(identifier: .gregorian)
+    calendar.timeZone = TimeZone(identifier: "UTC")!
+    return calendar
+}()
+
+/// Builds a date in the UTC test calendar. 2025-01-06 is a Monday; the tests
+/// use that week (Jan 6–12, 2025) as their anchor.
+func date(
+    _ year: Int, _ month: Int, _ day: Int, _ hour: Int = 0, _ minute: Int = 0
+) -> Date {
+    utc.date(
+        from: DateComponents(year: year, month: month, day: day, hour: hour, minute: minute)
+    )!
+}
+
+/// Monday of the anchor week.
+enum AnchorWeek {
+    static let monday = (year: 2025, month: 1, day: 6)
+    static let tuesday = (year: 2025, month: 1, day: 7)
+    static let wednesday = (year: 2025, month: 1, day: 8)
+    static let saturday = (year: 2025, month: 1, day: 11)
+    static let sunday = (year: 2025, month: 1, day: 12)
+    static let nextMonday = (year: 2025, month: 1, day: 13)
+}