fix: satisfy deploy lint gate for S3 compatibility work

- Apply Biome organize-import/formatting fixes across changed S3 files
- Replace remaining string concatenations with template literals for lint
- Make home page inline handlers explicit via window.* and add button types
- Clean S3 auth lint issues with dot-property access and optional chaining
- Keep GetObject proxy and production/S3 SDK tests passing

Verification:
- bun run lint (0 errors, 1 CSS specificity warning)
- S3_SECRET_KEY=<env> bun test test/production-e2e.test.ts (29 pass)
- S3_SECRET_KEY=<env> bun test test/s3-sdk.test.ts (20 pass)
- bun test test/s3-auth.test.ts (5 pass)

test/s3-auth.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, beforeAll } from 'bun:test';
+import { beforeAll, describe, expect, it } from 'bun:test';
 
 describe('S3 Auth (SigV4)', () => {
   let verifySignature: typeof import('../src/utils/s3/auth').verifySignature;