chore: add linting, formatting, and type-checking

Add ESLint, Prettier, and TypeScript config files extending the shared
Headlamp plugin configs. Add npm scripts for lint/format. Auto-fix
existing source files. Add CI workflow for PRs and main pushes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/api/polaris.ts

@@ -157,7 +157,7 @@ export function usePolarisData(refreshIntervalSeconds: number): PolarisDataState
       return;
     }
     const intervalId = window.setInterval(() => {
-      setTick((t) => t + 1);
+      setTick(t => t + 1);
     }, refreshIntervalSeconds * 1000);
     return () => window.clearInterval(intervalId);
   }, [refreshIntervalSeconds]);