Give the collections sidebar its own Slint global

AppWindow carried the sidebar's tree, its row menu, renaming, drag and
drop between rows, the trash row, and the membership sheet as ~40
properties and callbacks on the root component, in the pattern CH-1
describes and the develop screen's globals (Adjustments, Framing, Steps,
...) already replaced. Collections.* in collections.slint now holds that
state, declared next to the MembershipRow struct it and the membership
sheet both use; Rust reaches it through window.global::<Collections>()
instead of window.set_/get_/on_/invoke_ on the root.

collection-selected, collection-select, and collection-offline-menu stay
on AppWindow: library_ui.rs invokes collection-select directly and
registers collection-offline-menu's handler, and lib.rs reads
collection-selected for back-navigation, so moving them would have meant
editing library_ui.rs, which another change on this branch is splitting
into a module directory. collections-visible stays too — it is
lib.rs's panel-layout state, seeded from the saved layout before the
sidebar exists, and collections_ui never touches it. Everything prefixed
library- (the grid's drag, selection and keyword state that the sidebar's
Rust also wires for cross-feature gestures like filing a selection into
a collection) stays on the window as well, since it belongs to the
library screen, not the sidebar.

ui/dr-ui/src/collections_ui/tree_sync.rs

@@ -11,9 +11,9 @@ use std::rc::Rc;
 use dr_catalog::collections::{self as coll, CollectionKind};
 use dr_catalog::Catalog;
 use dr_types::{CollectionId, ImageId};
-use slint::Model as _;
+use slint::{ComponentHandle as _, Model as _};
 
-use crate::{AppWindow, CollectionRow};
+use crate::{AppWindow, CollectionRow, Collections};
 
 use super::controller::CollectionsController;
 
@@ -27,7 +27,9 @@ pub fn refresh_tree(window: &AppWindow, ctl: &Rc<CollectionsController>, catalog
     let rows = match coll::tree(catalog.connection()) {
         Ok(r) => r,
         Err(e) => {
-            window.set_collection_error(format!("reading collections: {e}").into());
+            window
+                .global::<Collections>()
+                .set_collection_error(format!("reading collections: {e}").into());
             return;
         }
     };
@@ -95,7 +97,9 @@ pub fn refresh_tree(window: &AppWindow, ctl: &Rc<CollectionsController>, catalog
     *ctl.row_smart.borrow_mut() = smart;
     *ctl.row_has_children.borrow_mut() = has_kids;
     *ctl.row_nested.borrow_mut() = nested;
-    window.set_collection_rows(slint::ModelRc::new(slint::VecModel::from(out)));
+    window
+        .global::<Collections>()
+        .set_collection_rows(slint::ModelRc::new(slint::VecModel::from(out)));
 
     // The rows are what `sync_reorderable` reads, so it has to be told they
     // changed: a collection that gains a child, or one that is deleted out from
@@ -251,7 +255,7 @@ pub fn sync_selection(window: &AppWindow, ctl: &Rc<CollectionsController>, ids:
 /// looking at, and a scope change costs no extra query.
 pub(super) fn sync_reorderable(window: &AppWindow) {
     let id = window.get_collection_selected();
-    let rows = window.get_collection_rows();
+    let rows = window.global::<Collections>().get_collection_rows();
     let manual = id > 0
         && (0..rows.row_count())
             .filter_map(|i| rows.row_data(i))
@@ -346,7 +350,9 @@ pub(super) fn refresh_membership(
     let rows = match coll::membership_of(catalog.connection(), &chosen) {
         Ok(r) => r,
         Err(e) => {
-            window.set_collection_error(format!("reading collections: {e}").into());
+            window
+                .global::<Collections>()
+                .set_collection_error(format!("reading collections: {e}").into());
             Vec::new()
         }
     };
@@ -367,7 +373,9 @@ pub(super) fn refresh_membership(
         })
         .collect();
 
-    window.set_membership_rows(slint::ModelRc::new(slint::VecModel::from(out)));
+    window
+        .global::<Collections>()
+        .set_membership_rows(slint::ModelRc::new(slint::VecModel::from(out)));
 }
 
 #[cfg(test)]