chore(frontend): add Prettier configuration

- Configure printWidth: 100, singleQuote: true, trailingComma: es5
- Add Angular template parser override
- Ignore dist, node_modules, .angular, coverage
- Ignore generated GraphQL types

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/frontend/.prettierignore

@@ -0,0 +1,8 @@
+dist/
+node_modules/
+.angular/
+coverage/
+*.min.js
+*.min.css
+package-lock.json
+src/app/core/graphql/generated/

src/frontend/.prettierrc

@@ -0,0 +1,20 @@
+{
+  "printWidth": 100,
+  "tabWidth": 2,
+  "useTabs": false,
+  "semi": true,
+  "singleQuote": true,
+  "trailingComma": "es5",
+  "bracketSpacing": true,
+  "arrowParens": "avoid",
+  "endOfLine": "lf",
+  "htmlWhitespaceSensitivity": "css",
+  "overrides": [
+    {
+      "files": "*.html",
+      "options": {
+        "parser": "angular"
+      }
+    }
+  ]
+}