[everpcpc]

Goal

In the collection "Add series" and read list "Add books" dialogs, the selection count and the Cancel/confirm buttons sat at the end of the scrollable content. With a large library the infinite-loading grid keeps growing as you approach the bottom, so the confirm button is effectively unreachable — reported in #261, which asks for the actions to live at the top.

Changes

Both picker dialogs now use the Dialog fill layout so children manage their own scrolling:

• the selection count and Cancel/confirm buttons move to a fixed row directly under the search box, as the issue requests
• the result grid is the only scrolling area; infinite loading is unchanged

Test

• pnpm lint and pnpm build (tsc + vite) pass
• Manual, against a library of 30 series: the action row stays fixed at the top while the grid scrolls; scrolling to the bottom still triggers the next page; selecting series updates the count and enables confirm; confirming adds the series to the collection

Closes #261