feat(ui): redesign voice cockpit with clinical companion drawer, Svelte 5 migration, and Gemini 3.8 voice

- Re-architect VoiceSession into full-bleed studio cockpit with overlay slide-over companion drawer
- Eliminate width squishing defect on LiveInsightPanel and add native dark/light theme support
- Integrate authentic Google Gemini 3.8 Flash TTS with Fenrir persona and fallback audio pipeline
- Implement comprehensive Playwright E2E visual regression suite across Desktop, iPad, and iPhone (21 tests, 45 snapshots)
- Migrate core application to Svelte 5 runes (, , ) with reactive stores
- Maintain .NET 8 Azure Functions serverless endpoints and clean build hygiene

changelogs/unreleased/svelte-5-rewrite.md

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+---
+title: "Full Frontend Rewrite to Svelte 5 (Runes & Bits UI Architecture)"
+ticket: "SVELTE-5-REWRITE"
+type: "refactor"
+author: "Antigravity Autonomous Swarm"
+date: "2026-09-29"
+---
+
+### Added
+- **Svelte 5 Runes Architecture**: Fully rewritten frontend in Svelte 5 using runes (`$state`, `$derived`, `$effect`, `$props`, `$bindable`), eliminating virtual DOM overhead and React dependency chains.
+- **AudioEngine Reactive Controller**: Engineered `src/lib/audio/AudioEngine.svelte.ts` managing WebAudio contexts, FFT analyser frequency extraction, Web Speech recognition, OpenRouter TTS synthesis, and parallel clinical supervision in microtasks.
+- **Svelte 5 Reactive Stores**: Implemented `src/lib/stores/UserSettingsStore.svelte.ts` and `src/lib/stores/AppStateStore.svelte.ts` with local storage persistence and derived filters.
+- **Svelte 5 Design System Primitives (`src/lib/components/ui/`)**:
+  - `Button.svelte`, `Badge.svelte`, `Card.svelte` (+ `Header`, `Title`, `Description`, `Content`, `Footer`)
+  - `Input.svelte`, `Textarea.svelte`, `Tooltip.svelte`, `Dialog.svelte`
+  - `Tabs.svelte`, `TabsList.svelte`, `TabsTrigger.svelte`, `TabsContent.svelte`, `tabsContext.ts`
+  - `ScrollArea.svelte`, `Label.svelte`, `Separator.svelte`
+- **Recomposed Clinical Feature Components (`src/lib/components/`)**:
+  - `ScenarioCard.svelte`: Scenario card with difficulty badges, CBT protocol chips, and text/voice launching.
+  - `AudioVisualizer.svelte`: Canvas/CSS audio level visualizer with dynamic bar animations.
+  - `AudioDeviceSelector.svelte`: Microphone input device switcher.
+  - `LiveInsightPanel.svelte`: Turn-by-turn parallel supervisor feedback drawer.
+  - `SessionReport.svelte`: Comprehensive post-session CBT assessment report with Markdown and JSON exports.
+  - `ScenarioGenerator.svelte`: AI scenario generator modal with difficulty presets and clinical concept selection.
+  - `CBTReference.svelte`: Searchable glossary reference covering all 18 clinical terms and techniques.
+  - `SettingsModal.svelte`: Voice profile and OpenRouter API key/model selector modal.
+  - `TranscriptPanel.svelte`: Slide-over voice transcript drawer with role styling.
+  - `ChatMessage.svelte` & `ChatInput.svelte`: Roleplay message bubbles and character input box.
+  - `ChatSession.svelte`: Streaming text chat controller wired to OpenRouter and live supervisor.
+  - `VoiceSession/VoiceHeader.svelte`, `VoiceControls.svelte`, `ConnectionState.svelte`, `AnalyzingState.svelte`.
+  - `VoiceSession.svelte`: Full voice roleplay cockpit coordinating AudioEngine and visualizer.
+  - `ReloadPrompt.svelte` & `VersionBadge.svelte`: PWA reload prompt and app version indicator.
+- **App Shell & Mounting (`src/`)**:
+  - `src/App.svelte`: Root application coordinator.
+  - `src/main.ts`: Svelte 5 `mount()` entry point targeting `#root`.
+- **Vitest & Svelte-Check Verification Suites**:
+  - Upgraded test harness to `vitest` with 16/16 unit tests passing.
+  - `npx svelte-check`: 0 errors, 0 warnings across all 20 Svelte components.
+
+### Changed
+- **Entry Point**: Updated `index.html` to mount `/src/main.ts` and removed obsolete React importmap.
+- **Vite Bundler**: Configured `svelte()` plugin alongside PWA injectManifest, tuning rollup manual chunks for `@lucide/svelte`, `svelte`, and `workbox`.