[epic] Add support for clustering text chunks by embeddings

[triathematician]

• [x] Clustering chunks
  • [x] #308
  • [x] #309
  • [x] #310
  • [x] #311
• [x] Improved Text Manager UI
  • [x] #300
  • [x] #302
  • [x] #307
• [x] Clustering UI
  • [x] #301