SedaUI: ship an optional SwiftUI settings and push-to-talk panel

[pnegahdar]

Outcome

A macOS app can add a polished Seda settings surface and a working push-to-talk reference panel without rebuilding model management UI.

Public API

import SedaKit
import SedaUI

@State private var shortcut = SedaShortcut.shift

Settings {
    SedaSettingsView(runtime: seda, shortcut: $shortcut)
}

For a menu-bar or overlay experience:

SedaPushToTalkPanel(
    runtime: seda,
    shortcut: shortcut,
    onRevision: editor.replaceTranscript
)

Surface

• model profile, language, installed state, size, install progress, retry, and remove
• microphone permission and selected input device
• configurable hold shortcut, including the requested Shift-to-talk behavior
• compact recording state, live revision text, elapsed time, cancel, and commit
• actionable offline, permission, storage, and model errors
• accessible keyboard navigation, VoiceOver labels, reduced motion, light/dark mode

Architecture

• Keep SedaUI an optional target; SedaKit must have no SwiftUI dependency.
• Use a @MainActor observable controller over the SedaKit actor.
• The panel consumes revision events; it does not duplicate recognition logic.
• Provide shortcut and insertion protocols so host apps can use their own global-hotkey and editor integrations.
• Include a signed-off reference menu-bar app in the repository, but keep app policy out of the core library.

Acceptance criteria

• settings scene and embeddable view both work
• press, hold, partial revisions, release, final transcript path is integration-tested
• model install and removal path is integration-tested
• permission denied and model failure states have snapshot/UI tests
• sample app demonstrates editor insertion without Seda requiring Accessibility permission
• API docs show a complete app entry point, not disconnected snippets
• GitHub Actions builds and tests SedaKit, SedaUI, and the sample app on macOS

Dependency

Blocked by #7 for the in-process Swift runtime and microphone session API.