feat(api,userbot,frontend): add accounts from the web ui and isolate per-account settings

frontend/src/lib/styles/dialogs.scss

@@ -0,0 +1,66 @@
+.dialog-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: var(--z-modal);
+  background-color: rgba(0, 0, 0, 0.5);
+}
+
+.dialog-content {
+  position: fixed;
+  z-index: var(--z-modal);
+  top: 50%;
+  left: 50%;
+  transform: translate(-50%, -50%);
+
+  display: flex;
+  flex-direction: column;
+
+  width: min(32rem, 92vw);
+  max-height: 80vh;
+  border-radius: var(--border-radius-default);
+
+  background-color: var(--color-background);
+  box-shadow: 0 0.5rem 2rem var(--color-default-shadow);
+  outline: none;
+}
+
+.dialog-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+
+  padding: 1rem 1.25rem;
+  border-bottom: 1px solid var(--color-borders);
+}
+
+.dialog-title {
+  margin: 0;
+  font-size: 1.125rem;
+  font-weight: var(--font-weight-medium);
+}
+
+.dialog-close {
+  cursor: pointer;
+  display: flex;
+  padding: 0.375rem;
+  border: 0;
+  border-radius: 50%;
+  color: var(--color-text-secondary);
+  background-color: transparent;
+
+  &:hover {
+    background-color: var(--color-chat-hover);
+  }
+}
+
+.dialog-body {
+  overflow-y: auto;
+  padding: 1.25rem;
+}
+
+.dialog-actions {
+  display: flex;
+  gap: 0.75rem;
+  justify-content: flex-end;
+  padding: 0 1.25rem 1.25rem;
+}

frontend/src/lib/styles/global.scss

@@ -1,6 +1,7 @@
 @use "variables";
 @use "spacing";
 @use "forms";
+@use "dialogs";
 @use "dark-theme";
 
 html,