refactor(setup): consolidate prettier config and streamline CI

- Replace scattered .prettierignore files with a single root config
- Add scripts/ci.js to orchestrate lint, format, typecheck, commitlint, and build
- Simplify ci.yml to use ci.js and npm ci
- Apply prettier formatting to docs, locales, and HTML files

.prettierignore

@@ -0,0 +1,8 @@
+# Prompt templates (formatted manually for LLM readability)
+*prompt.md
+
+# Generated
+packages/extension/.wxt
+
+# Vendored
+**/components/ui