Tags retire from capture, a tidier attach, and an editable Space name

Three small fidelity fixes. Free-text tags are now fully gone from the UI — type retired tags as a concept, and this clears them from the last places they still showed up: Memory and Space capture and detail, plus the asset and insight detail views. The composer's attach control is now a compact "Attach" chip (paperclip + label) instead of a full drop box, matching the design; drag-and-drop still works, and the dedicated upload page keeps its large dropzone. And Space Owners can now rename a Space: the Space settings → Details tab has an editable Space name field alongside the description, saved together with one Save changes button.