Counterwork seemingly unclickable repo button labels (#15064)

As title, the change counter-works the effect from #14926 that links seem unclickable (especially in the default gitea theme), while maintaining some sort of visual harmony.

Co-authored-by: Andrew Thornton <art27@cantab.net>

web_src/less/_base.less

@@ -97,6 +97,7 @@
   --color-input-border-hover: #cecece;
   --color-navbar: #f8f8f8;
   --color-light: #00000006;
+  --color-light-mimic-enabled: rgba(0, 0, 0, calc(6 / 255 * 222 / 255 / var(--opacity-disabled)));
   --color-light-border: #0000001d;
   --color-hover: #0000000f;
   --color-active: #00000014;

web_src/less/_repository.less

@@ -2932,8 +2932,23 @@ tbody.commit-list {
   align-items: center;
 }
 
+.repo-buttons .ui.labeled.button > .label:hover {
+  color: var(--color-primary-light-2);
+  background: var(--color-light);
+}
+
+.label-mimic-enabled() {
+  color: var(--color-text-dark);
+  background: var(--color-light-mimic-enabled) !important;
+
+  &:hover {
+    color: var(--color-primary-dark-1);
+  }
+}
+
 .repo-buttons button[disabled] ~ .label {
   opacity: var(--opacity-disabled);
+  .label-mimic-enabled();
 }
 
 .repo-buttons .ui.labeled.button {
@@ -2947,6 +2962,10 @@ tbody.commit-list {
   &.disabled {
     pointer-events: inherit !important;
 
+    > .label {
+      .label-mimic-enabled();
+    }
+
     > .button {
       pointer-events: none !important;
     }

web_src/less/themes/theme-arc-green.less

@@ -92,6 +92,7 @@
   --color-input-border-hover: #505667;
   --color-navbar: #2a2e3a;
   --color-light: #00000028;
+  --color-light-mimic-enabled: rgba(0, 0, 0, calc(40 / 255 * 222 / 255 / var(--opacity-disabled)));
   --color-light-border: #ffffff28;
   --color-hover: #ffffff10;
   --color-active: #ffffff16;