HB-21 Fix request deliverable modal scroll / overflow behavior

[Christiantyemele]

• Type: Bug
• Priority: P2
• Source: bug-photo p12 bottom
• Problem:
  • The request-deliverable modal is called out for broken scrolling.
  • This makes a working feature feel incomplete or unusable on smaller screens.
• Acceptance criteria:
  • Long request forms remain fully accessible without clipped inputs or hidden CTA buttons.
  • Modal content scrolls independently when needed on laptop and mobile viewport sizes.
• Likely touched areas:
  • likelee-ui/src/components/agency/AgencyDeliverablesView.tsx
  • shared dialog / sheet styles if the issue is systemic