feat: copy a file's or folder's #/name@owner link from Files, Music, Photos and Search

"Copy link" puts the address group-link.js resolves on the clipboard, on the
hub's origin rather than the page's, so a link copied in the desktop
application is not app://meshbay. Files offers it for one row, from the
right-click menu or the toolbar with one row ticked (a phone's way in);
Music on one track's menu, whose dots a phone has; Photos on a right-clicked
tile and in the lightbox's bar. The video player and the file preview carry
a link button next to Download.

Applications get a `linkFor(entry | folderPath)` prop (MESHBAY_DESIGN.md
§9.2) and offer the action only when it names a link. The group page builds
it from the hub's row; Search from each result's own group and its path
before the merged views prefixed it, and names no link for a folder of the
merged tree, which a group name alone does not identify.

harness/copy_link_probe.py mounts the three applications in Chrome and reads
what reached the clipboard.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/icon.js b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
index 4fa4357..4d549f1 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/icon.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
@@ -65,6 +65,8 @@ const ICON_PATHS = {
   plus:     ['M12 5v14', 'M5 12h14'],
   refresh:  ['M20 11a8 8 0 0 0-15.3-2', 'M4 5v4h4',
              'M4 13a8 8 0 0 0 15.3 2', 'M20 19v-4h-4'],
+  link:     ['M10 13.5a4.5 4.5 0 0 0 6.4.4l3-3a4.5 4.5 0 0 0-6.4-6.4l-1.6 1.6',
+             'M14 10.5a4.5 4.5 0 0 0-6.4-.4l-3 3a4.5 4.5 0 0 0 6.4 6.4l1.6-1.6'],
   clip:     ['M20.5 11.8l-8.4 8.4a5.4 5.4 0 0 1-7.6-7.6l8.8-8.8a3.6 3.6 0 0 1 5.1 5.1l-8.8 8.8a1.8 1.8 0 0 1-2.5-2.5l8.1-8.1'],
   pencil:   ['M4 20h4l10.5-10.5a2.1 2.1 0 0 0-3-3L5 17v3',
              'M14.5 6.5l3 3'],