Unify UI workflows and streamline fleet management

src/lib/ui/components/primitives/Button.svelte

@@ -45,8 +45,9 @@
         aria-label={ariaLabel}
         {title}
         href={disabled || loading ? undefined : href}
-        role="button"
-        tabindex="0"
+        tabindex={disabled || loading ? -1 : undefined}
+        aria-busy={loading}
+        onclick={(event) => { if (disabled || loading) event.preventDefault(); else onclick?.(event); }}
     >
         {#if leading}<span class="slot slot-leading">{@render leading()}</span>{/if}
         <span class="label">{@render children?.()}</span>
@@ -60,6 +61,7 @@
         {type}
         {title}
         aria-label={ariaLabel}
+        aria-busy={loading}
         disabled={disabled || loading}
         {onclick}
     >
@@ -81,7 +83,8 @@
         font-family: var(--font-body);
         font-weight: var(--weight-semibold);
         letter-spacing: var(--tracking-normal);
-        line-height: 1;
+        line-height: 1.35;
+        min-height: 40px;
         cursor: pointer;
         text-decoration: none;
         border: 1px solid transparent;
@@ -105,7 +108,7 @@
     .btn:active:not(:disabled):not([aria-disabled='true']) { transform: translateY(0.5px); }
 
     /* Sizes */
-    .s-sm { padding: 6px 12px; font-size: var(--text-xs); border-radius: var(--radius-sm); }
+    .s-sm { min-height: 32px; padding: 6px 12px; font-size: var(--text-xs); border-radius: var(--radius-sm); }
     .s-md { padding: 9px 16px; font-size: var(--text-sm); }
     .s-lg { padding: 12px 22px; font-size: var(--text-base); }