UI: Make resending ARIs from Build Tab more intuitive

The current process to resend a previously encoded ARI:

1. Go to Build Tab
2. Select one or more entries then scroll down to 'Send Agents', OR click the CBOR Encoded String
3. Select checkbox on agent(s) you want to send it to
4. Press 'Manage'
5. Toggle 'ARI Builder'
6. ARI is pre-populated

A more intuitive process would simplify the above to:
3. Open a new popup dialog with the list of Agents to select and a preview of selected ARI.
4. Preview should show user BOTH the CBOR-Encoded HEX and ARI form if available
5. Button to (re)send selected, and a second button to 'Edit' that would open a pre-populated version of the 'ARI Builder' to edit

Related improvements:

• 'Send Agents' and pagination buttons shouldn't require scrolling to the bottom of the page. These should be pinned outside of the scrollable area
• Checkbox column on Agents view should NOT trigger 'Agent details' popup (this is too easy to accidentally click). We may want to add an info icon instead that is clickable

Related improvements moved to #402

Start in the Build Tab flow around Send Agents, CBOR Encoded String, and the ARI Builder. Trace how selected entries and agents are currently handled, then define the popup's ARI previews, agent selection, resend action, and edit action. Done means the simplified flow supports resending and opening a pre-populated ARI Builder without the existing multi-step navigation.