Keep approvals and Touch ID prompts focused without bringing the app forward

[sudoHG]

Refs #127

Problem

Presenting an approval called NSApp.activate(ignoringOtherApps:) so the panel could take keyboard focus. Activation brings every open Ask Key window forward, so whenever the management window was open behind other apps, each approval pulled it to the front together with the prompt. Ask Key is a menu-bar app; the prompt should appear on its own. (Present since v0.1.0, reported during the v0.2.0 acceptance.)

Change

• The approval panel is a non-activating panel (.nonactivatingPanel, becomesKeyOnlyIfNeeded = false): it becomes key and receives Return and Esc without activating the app. Its level (.modalPanel), space behavior and hidesOnDeactivate = false are unchanged.
• The explicit NSApp.activate before presenting an approval is removed. Opening the management window from the menu bar still activates the app.
• AgentApprovalPanelTests asserts the non-activating style and that the panel can become key.

Touch ID prompt focus

The Touch ID prompt is shown by a separate authentication process (--askkey-authenticate) that never activated itself, so the prompt appeared without focus and the sensor was not ready until the user clicked it (reveal plaintext, unlock, approval with authentication). The authentication process now activates itself before evaluatePolicy, and the app yields activation to it when the app is active.

Checks

• swift build: passed.
• swift test --filter 'AgentApprovalPanelTests|ApprovalPrompt': 9 passed, 0 failed.
• swift test --filter ManagementAuthentication: 24 passed, 0 failed.
• python3 scripts/check_hygiene.py, python3 scripts/check_module_deps.py: passed.
• Full suite and the approval desktop flows (button clicks, Esc): this PR's CI.