fix: deepen opens the linked note, task list columns in "Alle Aufgaben", Whisper repeats, date field

- The deepen buttons of task rows and Kanban cards open an already linked note (accent colour)
  instead of creating another one; the server refuses a second note for a linked task as well.
- "Alle Aufgaben" uses each task's own list columns for the status selector, dot and detail.
- Whisper: send vad_filter (STT_VAD_FILTER, default on) and drop a verbatim repeated tail of
  sentences or words from the transcript.
- Task detail: narrower time field, wider date field in the desktop sidebar.

v0.37.2.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/thoughts.go

@@ -311,6 +311,12 @@ func (s *Store) UpdateThoughtTriage(userID, thoughtID, action, convertTo, target
 			convertedType = "task"
 		} else if convertTo == "document" {
 			isTask := thought.Status == domain.StatusKept || (thought.Status == domain.StatusConverted && thought.ConvertedType == "task")
+			// A task already linked to a note keeps that note; no second one
+			if isTask && thought.ConvertedType == "document_block" && thought.DocID != "" {
+				if doc, err := s.GetDocumentByID(userID, thought.DocID); err == nil && doc != nil {
+					return thought, nil
+				}
+			}
 			newStatus = domain.StatusConverted
 			convertedType = "document"
 			title := thought.Content