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

.env.example

@@ -1 +1,4 @@
-VITE_GEMINI_API_KEY=""
+# Cognitive Clarity - Environment Configuration
+# OpenRouter API Key for local development (optional if configured via in-app Settings modal)
+VITE_OPENROUTER_API_KEY=""
+OPENROUTER_API_KEY=""