[thesiti92]

Sharing a board today mints a new /s/<capability> URL on every share, so one board ends up with several links and every link a receiver opens becomes another copy on Home. This makes a share link belong to the board: the first share mints the URL, every later share from that board uploads a new revision behind the same URL, and the URL always serves the newest revision.

Server side lands in cloudboard (schema split into share_link + revisions, newest-revision resolution, ?rev=); this PR is the Desktop half.

• Protocol 0.5.0: shareLink(origin, capability, revision?) / parseShareLink carry ?rev=; tolerant schemas for the revision list and shared meta; shareCreatedSchema stays strict so shipped builds keep working.
• Host: the share popover keys its link by board and re-uploads only when the board version changed (the server dedupes equal versions); import asks the service which revision a link serves before opening a copy, refreshes a receiver's unedited copy in place, imports a sibling copy beside an edited one, pins copies opened from ?rev= links, and opens the newest local copy when the service cannot answer. Legacy copies match their revision by sharedAt.
• Store: copiesOf(key) and refreshCopy (same board id, Trash kept, 409 past baseVersion, refuses non-copies).
• Deep link dev-fast-review://share/<token>?rev= carries the revision.
• Journeys: share-link (share, edit, reshare, URL unchanged) and shared-review now covers refresh in place, the edited-copy path and offline reopen, against a fake share service.

Stacked on #1470 (protocol 0.4.0). A follow-up PR adds the history list and Revoke to the popover.