fix(model-manager): replace window.confirm with in-app modal

Browsers suppress native confirm() dialogs after repeated use (the
"prevent this page from creating additional dialogs" checkbox), which
silently broke deletes. Add a promise-based in-app confirmation modal
and use it for gallery photo and installed-model deletes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

model-manager/app/static/app.js

@@ -32,6 +32,33 @@ function fmtDate(epoch) {
   return new Date(epoch * 1000).toLocaleString();
 }
 
+// In-app confirmation dialog (replaces window.confirm, which browsers can
+// suppress after repeated use). Returns a Promise<boolean>.
+function confirmDialog(message, okLabel = "Delete") {
+  return new Promise((resolve) => {
+    const overlay = $("#confirmModal");
+    $("#confirmMsg").textContent = message;
+    $("#confirmOk").textContent = okLabel;
+    overlay.hidden = false;
+    const done = (val) => {
+      overlay.hidden = true;
+      $("#confirmOk").onclick = null;
+      $("#confirmCancel").onclick = null;
+      overlay.onclick = null;
+      document.removeEventListener("keydown", onKey);
+      resolve(val);
+    };
+    function onKey(e) {
+      if (e.key === "Escape") done(false);
+      if (e.key === "Enter") done(true);
+    }
+    $("#confirmOk").onclick = () => done(true);
+    $("#confirmCancel").onclick = () => done(false);
+    overlay.onclick = (e) => { if (e.target === overlay) done(false); };
+    document.addEventListener("keydown", onKey);
+  });
+}
+
 // ---- navigation -----------------------------------------------------------
 
 function showView(name) {
@@ -118,7 +145,7 @@ function renderModels(models) {
 }
 
 async function deleteModel(m) {
-  if (!confirm(`Delete ${m.name}?`)) return;
+  if (!(await confirmDialog(`Delete ${m.name}?`))) return;
   try {
     await api("/api/models", {
       method: "DELETE",
@@ -307,7 +334,7 @@ function renderPhotoCard(p) {
 }
 
 async function deletePhoto(p, card) {
-  if (!confirm(`Permanently delete ${p.name}?`)) return;
+  if (!(await confirmDialog(`Permanently delete ${p.name}?`))) return;
   try {
     await api("/api/gallery", {
       method: "DELETE",