Add missing fallbacks for disabled buttons (#735)

* add missing fallbacks

* Create pink-carpets-stare.md

.changeset/pink-carpets-stare.md

@@ -0,0 +1,5 @@
+---
+"@primer/primitives": patch
+---
+
+Add missing fallbacks for disabled buttons

src/tokens/fallback/color-fallbacks.json

@@ -103,9 +103,11 @@
   "--button-default-bgColor-hover": "var(--color-btn-hover-bg)",
   "--button-default-bgColor-active": "var(--color-btn-active-bg)",
   "--button-default-bgColor-selected": "var(--color-btn-selected-bg)",
+  "--button-default-bgColor-disabled": "var(--color-btn-bg)",
   "--button-default-borderColor-rest": "var(--color-btn-border)",
   "--button-default-borderColor-hover": "var(--color-btn-hover-border)",
   "--button-default-borderColor-active": "var(--color-btn-active-border)",
+  "--button-default-borderColor-disabled": "var(--color-btn-border)",
   "--button-default-shadow-resting": "var(--color-btn-shadow)",
   "--button-default-shadow-inset": "var(--color-btn-inset-shadow)",
   "--button-primary-fgColor-rest": "var(--color-btn-primary-text)",
@@ -128,6 +130,7 @@
   "--button-invisible-bgColor-disabled": "var(--color-action-list-item-default-selected-bg)",
   "--button-invisible-borderColor-rest": "transparent",
   "--button-invisible-borderColor-hover": "transparent",
+  "--button-invisible-borderColor-disabled": "var(--color-action-list-item-default-selected-bg)",
   "--button-outline-fgColor-rest": "var(--color-btn-outline-text)",
   "--button-outline-fgColor-hover": "var(--color-btn-outline-hover-text)",
   "--button-outline-fgColor-active": "var(--color-btn-outline-selected-text)",
@@ -152,6 +155,7 @@
   "--button-danger-borderColor-rest": "var(--color-btn-border)",
   "--button-danger-borderColor-hover": "var(--color-btn-danger-hover-border)",
   "--button-danger-borderColor-active": "var(--color-btn-danger-selected-border)",
+  "--button-danger-borderColor-disabled": "var(--color-action-list-item-default-selected-bg)",
   "--button-danger-shadow-selected": "var(--color-btn-danger-selected-shadow)",
   "--buttonCounter-default-bgColor-rest": "var(--color-btn-counter-bg)",
   "--buttonCounter-primary-bgColor-rest": "var(--color-btn-primary-counter-bg)",