feat(store): trust gate before every module install

One-click installs showed no trust signal at all (top security
finding of the usertest panel). Every install path — store card,
detail sheet, and the flow list's quick fix — now routes through
one confirmation dialog showing what the hub actually knows
before download: origin store, version, license, maturity, and
required services/capabilities, plus the sandbox model and an
honest note that per-entry signature status is not in the store
index yet (verification happens hub-side at install). Widget
tests cover content and confirm/cancel semantics.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/pages/store.dart

@@ -193,6 +193,11 @@ class _StorePageState extends State<StorePage> {
 
   Future<void> _install(StoreItem item) async {
     if (!mounted) return;
+    // Trust gate: provenance + sandbox/signature context BEFORE
+    // anything is downloaded (usertest: one-click install with
+    // no visible trust signal was the top security finding).
+    final confirmed = await ChainInstallConfirmDialog.show(context, item);
+    if (!confirmed || !mounted) return;
     final outcome = await showDialog<bool>(
       context: context,
       barrierDismissible: false,
@@ -2293,6 +2298,11 @@ class _StoreDetailSheetState extends State<_StoreDetailSheet> {
   }
 
   Future<void> _install() async {
+    // Same trust gate as the store card — the detail sheet's
+    // install button must not be a quieter bypass.
+    final confirmed =
+        await ChainInstallConfirmDialog.show(context, widget.item);
+    if (!confirmed || !mounted) return;
     setState(() {
       _busy = true;
       _toast = null;