fix: FilePreview fileType case + Tailwind v4 gradient transparent bug

- FilePreview.vue: add normalizedFileType computed to handle backend
  returning uppercase HTML/MD/PPTX (fixes preview/download buttons)
- FilePreview.vue: bg-gradient-to-r from-orange-500 -> bg-orange-500
  (Tailwind v4 gradient + CSS variable = transparent)
- ReportCard.vue: bg-gradient-to-r -> bg-orange-600 for selected state
- Add .opencode/, node_modules/, dist/ to .gitignore
- Initial git setup for publish project

playwright.config.js

@@ -0,0 +1,33 @@
+import { defineConfig, devices } from '@playwright/test'
+
+export default defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: false,
+  forbidOnly: !!process.env.CI,
+  retries: 0,
+  workers: 1,
+  reporter: 'list',
+  timeout: 60000,
+  expect: {
+    timeout: 10000
+  },
+  use: {
+    baseURL: 'http://127.0.0.1:41733',
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure'
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] }
+    }
+  ],
+  webServer: {
+    command: 'npm run dev',
+    url: 'http://127.0.0.1:41733',
+    reuseExistingServer: true,
+    timeout: 120000,
+    stdout: 'pipe',
+    stderr: 'pipe'
+  }
+})