feat: internal verstak:// link navigation (case/note/file)
1. handleVerstakLink now performs real navigation:
- case/<id>: GetNodeDetail → selectNode (selects node in tree)
- note/<id>: GetNodeDetail → find parent → selectNode(parent) → setActiveTab('notes') → openNote
- file/<id>: GetNodeDetail → find parent → selectNode(parent) → setActiveTab('files') → loadFolder → openPreview
- secret/<id>: toast 'Seaf access not implemented'
- missing ids: toast 'Not found'
2. Changed href from about:blank to # (safe, DOMPurify won't strip)
e.preventDefault() in click handler prevents scroll-to-top
3. Added i18n keys: caseNotFound, noteNotFound, fileNotFound, fileFound
4. All existing tests pass, build OK
mirivlad
db961ff0c3