Results in buttons having liquid glass effect on iOS 26 and no change on other iOS versions as those buttons were built the same way and up to the same spec.
• add "large primary", "large secondary", "medium secondary" SwiftUI button styles and use them.
• tweak subtitle font to match specs.
• use liquid glass button on iOS 26.
• bring back keyboard frame tracking to OWSViewController if running on iOS 15.
• add our own layout guide to OWSViewController that is updated based on keyboard frame notifications on iOS 15; on newer iOS versions it's a proxy to view.keyboardLayoutGuide.
• use OWSViewController.keyboardLayoutGuide where needed.
• in media composer screen (not OWSVIewController subclass) we already track keyboard frame - use that to position bottom toolbar on iOS 15.
I have also discovered that profile avatar editing screen was somewhat broken on older (15, 16) iOS versions. Fixed that here.
• make sticker / attachment keyboard follow system (text) keyboard height as closely as possible.
• fix chat input bar obscured by keyboard after interface rotation.
revious color was semi-opaque black which meant the resulting color of a selected UITableViewCell's background was not something referenced in the code. Therefore it wasn't easily possible to re-use the color for non-UITableViewCell elements (e.g. creating UIButton whose colors should match UITableView's colors). With the opaque colors final color of the background of a selected cell is known and can be referenced directly.
Also removed Theme.tableCell2MultiSelectedBackgroundColor - use one color for both "single" and "multiple" selection modes.
Fix Calls tab not setting UITableViewCell properly to use custom cell background color in multi-select mode.
It seems that UIKit extends system keyboard background above UIInputView subclass with the purpose of making top corners rounded. This temporary fix removes custom background color from attachment picker and sticker keyboards. The result is a system-provided background that looks okay.
Replace Theme.cellSeparatorColor with Theme.tableView2SeparatorColor in table views.
Replace Theme.cellSeparatorColor with Theme.hairlineColor everywhere else. This change is no-op as the former was returning the latter anyway.
