fix: doc rendering — markdown prose styling, code blocks with copy button, proper step parsing

- Add @tailwindcss/typography plugin for prose styling
- Create CodeBlock component with copy button and language labels
- Create Md wrapper component using ReactMarkdown with custom renderers
- Replace all plain text renders with Md for proper markdown formatting
- Fix parseSteps() in pipeline to group numbered steps with code blocks
- Add First Task subtitle explaining its purpose
- Add conditional file.purpose render in module key files

apps/web/package.json

@@ -12,6 +12,7 @@
   },
   "dependencies": {
     "@codeboard/shared": "*",
+    "@tailwindcss/typography": "^0.5.19",
     "bullmq": "^5.34.0",
     "ioredis": "^5.4.0",
     "lucide-react": "^0.563.0",