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

tests/e2e/01-landing-and-navigation.spec.ts

@@ -0,0 +1,66 @@
+import { test, expect } from '@playwright/test';
+import fs from 'fs';
+import path from 'path';
+
+test.describe('Landing Page & Scenario Navigation', () => {
+  test.beforeEach(async ({ page }) => {
+    // Clear localStorage to ensure fresh deterministic initial state
+    await page.addInitScript(() => {
+      window.localStorage.clear();
+      window.localStorage.setItem('cognitive-clarity-settings', JSON.stringify({
+        voiceName: 'Zephyr',
+        vocalStyle: 'Helpful',
+        genderPreference: 'Neutral',
+        openRouterApiKey: 'sk-or-v1-playwright-mock-key',
+        roleplayModel: 'google/gemini-3.8-flash',
+        supervisorModel: 'google/gemini-3.8-flash'
+      }));
+    });
+  });
+
+  test('01 - Home View Initial Render and Visual Snapshot', async ({ page }, testInfo) => {
+    await page.goto('/');
+    await page.waitForLoadState('networkidle');
+
+    // Verify Brand Hero & Elements
+    await expect(page.locator('h1')).toContainText('Cognitive Clarity');
+    await expect(page.getByText('Evidence-Based Framework')).toBeVisible();
+    await expect(page.getByText(/Vocal Partner:/)).toBeVisible();
+    await expect(page.getByRole('heading', { name: 'Training Scenarios' })).toBeVisible();
+
+    // Verify all 14 default scenarios are rendered
+    const scenarioCards = page.locator('[data-testid="scenarios-grid"] > *');
+    await expect(scenarioCards).toHaveCount(15); // 14 scenarios + 1 custom trigger button
+
+    // Capture visual snapshot
+    const shotDir = path.join(process.cwd(), 'docs/screenshots', testInfo.project.name);
+    fs.mkdirSync(shotDir, { recursive: true });
+    await page.screenshot({ path: path.join(shotDir, '01-home-initial.png'), fullPage: true });
+  });
+
+  test('02 - Filter Scenarios by Difficulty', async ({ page }, testInfo) => {
+    await page.goto('/');
+    await page.waitForLoadState('networkidle');
+
+    // Filter by Beginner
+    await page.getByRole('button', { name: 'Beginner', exact: true }).click();
+    await expect(page.getByText('The Silent Friend')).toBeVisible();
+    await expect(page.getByText('Inner Critic Echo')).toBeVisible();
+
+    const shotDir = path.join(process.cwd(), 'docs/screenshots', testInfo.project.name);
+    fs.mkdirSync(shotDir, { recursive: true });
+    await page.screenshot({ path: path.join(shotDir, '02-filter-beginner.png'), fullPage: true });
+
+    // Filter by Advanced
+    await page.getByRole('button', { name: 'Advanced', exact: true }).click();
+    await expect(page.getByText('The Social Spotlight')).toBeVisible();
+    await expect(page.getByText('The Unpaid Debt')).toBeVisible();
+    await expect(page.getByText('The Silent Friend')).not.toBeVisible();
+
+    await page.screenshot({ path: path.join(shotDir, '03-filter-advanced.png'), fullPage: true });
+
+    // Reset to All
+    await page.getByRole('button', { name: 'All', exact: true }).click();
+    await expect(page.getByText('The Silent Friend')).toBeVisible();
+  });
+});