feat(ui): standardize design system, modals, sidebar, and form inputs

- Implement unified design system tokens, 10px radius, and IRANSans typography
- Modernize sidebar with Gemini-style collapsed expander, square 1:1 items, and elevated profile flyout
- Standardize all modal dialogs with 16px padding, fixed header/footer, 16px medium title, and sticky bottom actions
- Refactor DealFormView and CustomFieldsSection with standard UiField, UiInput, and UiSelect components
- Add draggable bottom-left QuickCreate floating action button

apps/web/src/components/brand/MentoAiAvatar.vue

@@ -64,7 +64,7 @@ withDefaults(
   width: max-content;
   max-width: 118px;
   padding: 0.48rem 0.65rem 0.55rem;
-  border-radius: 14px;
+  border-radius: var(--radius);
   background: #fff;
   color: #0f172a;
   font-size: 0.68rem;

apps/web/src/components/brand/MentoLogo.vue

@@ -56,7 +56,7 @@ withDefaults(
   letter-spacing: -0.02em;
   color: #0f172a;
   line-height: 1.1;
-  font-weight: 800;
+  font-weight: 600;
 }
 
 .text small {