build(eslint): focus-safe-disabled folds into button-primitive

Two rules looked at the same <button>: button-primitive refused a raw one
outside the control primitives, focus-safe-disabled refused a raw
`disabled` one everywhere but FocusSafeButton and AnchoredPopover. They are
one rule now, with the same reach: outside the primitives a raw button is
refused (a disabled one with the focus message); inside a primitive and in
a test only a raw `<button disabled>` is, and the two native-disabled owners
are named in the rule rather than in a config override. One override block,
one rule entry and two register rows go; the snapshot loses a config group.
focusSafe.contract.test.ts pins every case, the primitive and test ones new.

frontend/src/lib/gates.snapshot.json

@@ -1,48 +1,6 @@
 {
   "eslint": {
     "configs": {
-      "FocusSafeButton.tsx + AnchoredPopover.tsx": {
-        "languageOptions": {
-          "ecmaVersion": 2022,
-          "globals": "1169 names, sha1 aee621727a03",
-          "parser": "typescript-eslint/parser",
-          "parserOptions": { "projectService": true, "tsconfigRootDir": "." },
-          "sourceType": "module"
-        },
-        "linterOptions": { "reportUnusedDisableDirectives": 2 },
-        "notApplied": [],
-        "plugins": [
-          "@",
-          "@eslint-community/eslint-comments",
-          "@typescript-eslint",
-          "local",
-          "react-hooks",
-          "react-refresh"
-        ],
-        "rules": {
-          "local/focus-safe-disabled": [0],
-          "no-restricted-imports": [
-            2,
-            {
-              "patterns": [
-                {
-                  "message": "components/ui/ is domain-free: a platform component may not import a feature component. Invert the dependency (take a prop/render-prop) or keep the component outside ui/.",
-                  "regex": "^\\.\\./(?!\\.\\./)"
-                },
-                {
-                  "message": "components/ui/ is domain-free: a platform component may not import a feature component. Invert the dependency (take a prop/render-prop) or keep the component outside ui/.",
-                  "regex": "^\\.\\./\\.\\./components/(?!ui/)"
-                },
-                {
-                  "message": "components/ui/ is domain-free: a platform component may not call a domain API slice. Take the data as props.",
-                  "regex": "^\\.\\./\\.\\./lib/api(/|$)"
-                }
-              ]
-            }
-          ]
-        },
-        "settings": null
-      },
       "design-lab": {
         "languageOptions": {
           "ecmaVersion": 2022,
@@ -75,7 +33,6 @@
         "linterOptions": { "reportUnusedDisableDirectives": 2 },
         "notApplied": [
           "local/button-primitive",
-          "local/focus-safe-disabled",
           "local/glyph-link",
           "local/input-primitive",
           "local/jsx-comment-text",
@@ -158,7 +115,6 @@
           "@typescript-eslint/prefer-namespace-keyword",
           "@typescript-eslint/triple-slash-reference",
           "local/button-primitive",
-          "local/focus-safe-disabled",
           "local/glyph-link",
           "local/input-primitive",
           "local/jsx-comment-text",
@@ -248,7 +204,6 @@
           "vitest"
         ],
         "rules": {
-          "local/button-primitive": [0],
           "local/glyph-link": [0],
           "local/input-primitive": [0],
           "local/literal-a11y-text": [0],
@@ -711,7 +666,6 @@
           "linebreak-style": [0],
           "lines-around-comment": [0],
           "local/button-primitive": [2],
-          "local/focus-safe-disabled": [2],
           "local/glyph-link": [2],
           "local/input-primitive": [2],
           "local/jsx-comment-text": [2],
@@ -1062,7 +1016,6 @@
           "vitest"
         ],
         "rules": {
-          "local/button-primitive": [0],
           "local/glyph-link": [0],
           "local/input-primitive": [0],
           "local/literal-a11y-text": [0],
@@ -1153,7 +1106,6 @@
         "linterOptions": { "reportUnusedDisableDirectives": 2 },
         "notApplied": [
           "local/button-primitive",
-          "local/focus-safe-disabled",
           "local/glyph-link",
           "local/input-primitive",
           "local/jsx-comment-text",
@@ -1262,7 +1214,6 @@
           "vitest"
         ],
         "rules": {
-          "local/button-primitive": [0],
           "local/glyph-link": [0],
           "local/input-primitive": [0],
           "local/literal-a11y-text": [0],
@@ -1331,10 +1282,6 @@
     },
     "files": {
       "(not linted)": [],
-      "FocusSafeButton.tsx + AnchoredPopover.tsx": [
-        "src/components/ui/AnchoredPopover.tsx",
-        "src/components/ui/FocusSafeButton.tsx"
-      ],
       "design-lab": [
         "src/design-lab/DesignLab.tsx",
         "src/design-lab/batchA.tsx",
@@ -1959,6 +1906,7 @@
       ],
       "ui": [
         "src/components/ui/ActionMenu.tsx",
+        "src/components/ui/AnchoredPopover.tsx",
         "src/components/ui/Avatar.tsx",
         "src/components/ui/BackToTop.tsx",
         "src/components/ui/Badge.tsx",
@@ -1978,6 +1926,7 @@
         "src/components/ui/FilterChipGroup.tsx",
         "src/components/ui/FilterFold.tsx",
         "src/components/ui/FilterSelect.tsx",
+        "src/components/ui/FocusSafeButton.tsx",
         "src/components/ui/Headings.tsx",
         "src/components/ui/HiddenFilterCue.tsx",
         "src/components/ui/IconButton.tsx",