fix(drag): remove data-no-drag from extension window bodies to restore hold-to-drag
Commit szmkrrrvqlos added data-no-drag to all extension home.html <body>
elements to fix a click handling issue. However, the preload.js universal
drag system (initWindowDrag) checks target.closest('[data-no-drag]') to
decide whether to block drag — with data-no-drag on <body>, every click
inside the window matches, completely disabling hold-to-drag for all
extension windows (tags, groups, entities, editor, etc.).
Page windows (peek://page) correctly keep data-no-drag because they have
their own canvas-based drag system in page.js. Extension windows rely on
the preload.js drag system, so they must NOT have data-no-drag on body.
The preload drag system already handles interactive elements properly:
focused inputs/textareas and contentEditable elements block drag, and
click suppression only fires after an actual drag (80ms hold + movement).