Improved progress UI for AI-assisted imports

When you start an AI-assisted argument import and watch it from the argument view, the page now shows a clean pipeline stepper with one status line per active stage instead of a generic spinner. You'll see exactly which stages have run, which is currently working, and how long it's been on the current step.

If the AI service is temporarily unavailable and your import is cancelled in flight, you'll see a clear notice — "Cancelled — AI temporarily unavailable" — instead of a stuck spinner. You can revisit the task detail page or try again later.

Detailed pipeline view shows the inputs and outputs

On the task detail page (/task/<id>), clicking a stage now expands collapsible Input, Output, and Result sections — you can see the exact message that was sent to the AI and the structured result it returned for each attempt. The currently-selected stage is also visually highlighted in the stepper so it's clear which one you're inspecting.

Retry a failed import from the task detail page

If an AI-assisted import fails, the task detail page now shows a Retry import button next to the failure banner — and a per-stage Retry from this stage button inside the failed stage's detail. Either button opens a confirmation that explains the entire import re-runs from the beginning and that all stages are re-billed against your token budget, so there are no surprise charges. Confirming kicks off a fresh run and takes you to its task page so you can watch the new attempt from the start. If your monthly token budget is already exhausted, or the AI service is temporarily unavailable, the retry button is disabled with a tooltip explaining why.

Graceful platform-wide cool-down when AI services are temporarily unavailable

If the AI service provider runs into a quota or availability issue, Proposit now switches AI-assisted features off platform-wide for a short cool-down window (up to 24 hours) instead of failing imports one-by-one with confusing errors. While the cool-down is in effect, the AI-assisted import buttons and the retry button are visibly disabled with a tooltip that explains the temporary unavailability. Any import that was already running when the issue was detected is cancelled with a clear "Cancelled — AI temporarily unavailable" notice on the argument view so you're never stuck on a spinner. The cool-down clears automatically once service is restored.