Name the eye pass on the People screen

Once every image has been through the detector and only readings are
left — the state an already-indexed library is in the day the eye models
arrive — the button reads "Read eye state" rather than promising to
index, and the coverage line says what the faces are waiting for.

ui/dr-ui/ui/app.slint

@@ -406,6 +406,7 @@ export component AppWindow inherits Window {
     in property <string> identity-back-label: "‹ Library";
     in property <string> identity-coverage;
     in property <bool> identity-coverage-complete: false;
+    in property <bool> identity-coverage-read-only: false;
     in property <int> identity-picked: 0;
     /// The namesake merge the Identity screen is offering. See IdentityScreen.
     in property <string> identity-merge-offer-name;
@@ -1419,6 +1420,7 @@ in property <bool> panel-visible: true;
             back-label: root.identity-back-label;
             coverage: root.identity-coverage;
             coverage-complete: root.identity-coverage-complete;
+            coverage-read-only: root.identity-coverage-read-only;
             merge-offer-name: root.identity-merge-offer-name;
             merge-offer-faces: root.identity-merge-offer-faces;
             name-revision: root.identity-name-revision;