Fix product page layout alignment

[JacobLinCool]

Summary

• isolate the catalog FilterField from legacy search styling
• align profile settings with the standard product page frame while retaining a readable 760px form column
• add focused DOM and CSS regression coverage

Verification

• browser geometry at 2048×766, 760×900, and 390×844
• pnpm exec vitest run --config vitest.config.ts (160 files, 771 tests passed)
• pnpm run typecheck
• pnpm run lint
• git diff --check
• Jacob checkpoint: PASS