add buttons fix tasks

[satteomama]

Summary

Motivation

Changes

• Add sample tasks
  *Fix button interaction bug

How was this tested?

• [X ] npm run lint
• [X ] npm run typecheck
• [X ] npm run build
• [X ] Manual UI walkthrough (login → create → filter → edit → complete → delete → logout)
• [X ] API smoke tests with curl (see README "REST API reference")

Checklist

• Code follows the layer boundaries described in spec §1.4.1
  (presentation never touches the filesystem directly).
• New / changed API routes return appropriate HTTP status codes
  (200 / 201 / 400 / 401 / 404).
• Task routes still require the prismtask_user session cookie.
• No secrets, credentials, or personal data added to the repository.
• Commit messages follow Conventional Commits (feat: / fix: /
  refactor: / docs: / test: / chore:).

Screenshots / recordings