feat(workspace): allow sharing notes and shared folders as editor

The share dialog for notes and shared folders now offers "Bearbeiten" and
"Nur Lesen" and stores write/read accordingly. Editors already edit through
the sync engine since phase 2.

Adds e2e/share.e2e.mjs: shares a note as editor through the dialog and checks
that the recipient can edit it; e2e/run.sh runs both browser tests.

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

e2e/run.sh

@@ -15,4 +15,4 @@ for _ in $(seq 1 60); do curl -s -m 1 http://localhost:18080/api/v1/health >/dev
 
 echo "Starte Browser-Tests …"
 "$ENGINE" run --rm --network host -v "$ROOT/e2e":/e2e:Z -w /e2e mcr.microsoft.com/playwright:v1.48.2-jammy \
-  sh -c 'npm install --no-audit --no-fund >/dev/null 2>&1 && node collab.e2e.mjs'
+  sh -c 'npm install --no-audit --no-fund >/dev/null 2>&1 && node collab.e2e.mjs && node share.e2e.mjs'