fix: ai-jobs page empty list + missing Review button + no results in modal

Three bugs:

1. +page.server.ts returned an unawaited Promise — SvelteKit awaits it on
   the server anyway so data.jobs arrived as a plain AIJob[] on the client,
   not a Promise. The $effect calling .then() on an array silently failed,
   leaving jobs=[] and the table empty. Fixed by awaiting in the load fn.

2. +page.svelte $effect updated to assign data.jobs directly (plain array)
   instead of calling .then() on it.

3. handlers_textgen.go: final UpdateAIJob (payload+status write) used
   r.Context() which is cancelled when the SSE client disconnects. If the
   browser navigated away mid-job, results were silently dropped and the
   payload stayed as the initial {pattern} stub with no results array.
   Fixed by using context.Background() for the final write, matching the
   pattern already used in handlers_image.go.

backend/internal/backend/handlers_textgen.go

@@ -313,6 +313,8 @@ func (s *Server) handleAdminTextGenChapterNames(w http.ResponseWriter, r *http.R
 	}
 
 	// Mark job as done in PB, persisting results so the Review button works.
+	// Use context.Background() — r.Context() may be cancelled if the SSE client
+	// disconnected before processing finished, which would silently drop results.
 	if jobID != "" && s.deps.AIJobStore != nil {
 		status := domain.TaskStatusDone
 		if jobCtx.Err() != nil {
@@ -321,7 +323,7 @@ func (s *Server) handleAdminTextGenChapterNames(w http.ResponseWriter, r *http.R
 		resultsJSON, _ := json.Marshal(allResults)
 		finalPayload := fmt.Sprintf(`{"pattern":%q,"slug":%q,"results":%s}`,
 			req.Pattern, req.Slug, string(resultsJSON))
-		_ = s.deps.AIJobStore.UpdateAIJob(r.Context(), jobID, map[string]any{
+		_ = s.deps.AIJobStore.UpdateAIJob(context.Background(), jobID, map[string]any{
 			"status":     string(status),
 			"items_done": chaptersDone,
 			"finished":   time.Now().Format(time.RFC3339),