gitlab-ci: move macOS arm64 jobs to tart runners

`tart` uses VMs to execute jobs instead of running directly on the host.
Leave `macos-x86_64` jobs as `shell` runners so that there is still
testing on actual Intel hardware and to avoid linker crashes with
Rosetta inside of the Tart VMs.

.gitlab-ci.yml

@@ -939,7 +939,7 @@ t:macos-arm64-ninja-multi:
     extends:
         - .macos_arm64_ninja_multi
         - .cmake_test_macos_external
-        - .macos_arm64_tags_ext
+        - .macos_arm64_tags
         - .cmake_junit_artifacts
         - .run_dependent
     needs:
@@ -963,7 +963,7 @@ t:macos-arm64-xcode:
     extends:
         - .macos_arm64_xcode
         - .cmake_test_macos_external
-        - .macos_arm64_tags_ext
+        - .macos_arm64_tags
         - .cmake_junit_artifacts
         - .run_dependent
     needs:
@@ -973,7 +973,7 @@ t:macos-arm64-xcode-symlinked:
     extends:
         - .macos_arm64_xcode_symlinked
         - .cmake_test_macos_external
-        - .macos_arm64_tags_ext
+        - .macos_arm64_tags
         - .cmake_junit_artifacts
         - .run_dependent
     needs:
@@ -997,7 +997,7 @@ t:macos-arm64-xcode-ub:
     extends:
         - .macos_arm64_xcode_ub
         - .cmake_test_macos_external
-        - .macos_arm64_tags_ext
+        - .macos_arm64_tags
         - .cmake_junit_artifacts
         - .run_dependent
     needs:
@@ -1010,7 +1010,7 @@ b:macos-package:
         - .macos_package
         - .cmake_build_macos
         - .cmake_release_artifacts
-        - .macos_arm64_tags_package
+        - .macos_arm64_tags
         - .run_only_for_package
     needs:
         - p:doc-package
@@ -1029,7 +1029,7 @@ b:macos10.10-package:
         - .macos10.10_package
         - .cmake_build_macos
         - .cmake_release_artifacts
-        - .macos_arm64_tags_package
+        - .macos_arm64_tags
         - .run_only_for_package
     needs:
         - p:doc-package

.gitlab/os-macos.yml

@@ -6,10 +6,11 @@
     variables:
         GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci ext/$CI_CONCURRENT_ID"
 
-.macos_arm64:
-    extends: .macos
+.macos_tart:
+    image: "registry.hub.docker.com/kitware/macos-ci-images:macos-26-xcode-26.6-20260710"
     variables:
-        DEVELOPER_DIR: "/Applications/Xcode-26.4.app/Contents/Developer"
+        GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake-ci"
+        TART_EXECUTOR_HOST_DIR: "false"
 
 .macos_x86_64:
     extends: .macos
@@ -27,10 +28,9 @@
         # could run at the same time, so we drop it.
         GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci"
 
-.macos_arm64_build:
+.macos_tart_build:
     extends:
-        - .macos_arm64
-        - .macos_build
+        - .macos_tart
 
 .macos_x86_64_build:
     extends:
@@ -45,14 +45,14 @@
         CTEST_NO_WARNINGS_ALLOWED: 1
 
 .macos_arm64_ninja:
-    extends: .macos_arm64_build
+    extends: .macos_tart_build
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_ninja
         CTEST_NO_WARNINGS_ALLOWED: 1
 
 .macos_arm64_ninja_symlinked:
-    extends: .macos_arm64_build
+    extends: .macos_tart_build
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_ninja_symlinked
@@ -61,7 +61,7 @@
         CMAKE_CI_BUILD_DIR: "real_work/work/build"
 
 .macos_arm64_curl:
-    extends: .macos_arm64_build
+    extends: .macos_tart_build
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_curl
@@ -82,7 +82,7 @@
         CMAKE_GENERATOR: "Unix Makefiles"
 
 .macos_package:
-    extends: .macos_arm64_build
+    extends: .macos_tart_build
 
     variables:
         CMAKE_CONFIGURATION: macos_package
@@ -90,7 +90,7 @@
         CMAKE_CI_NO_INSTALL: 1
 
 .macos10.10_package:
-    extends: .macos_arm64_build
+    extends: .macos_tart_build
 
     variables:
         CMAKE_CONFIGURATION: macos10.10_package
@@ -108,7 +108,7 @@
         CMAKE_CI_NIGHTLY_IGNORE_DEPS: "true"
 
 .macos_arm64_xcode:
-    extends: .macos_arm64
+    extends: .macos_tart
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_xcode
@@ -116,7 +116,7 @@
         CMAKE_CI_NIGHTLY_IGNORE_DEPS: "true"
 
 .macos_arm64_xcode_symlinked:
-    extends: .macos_arm64
+    extends: .macos_tart
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_xcode_symlinked
@@ -126,7 +126,7 @@
         CMAKE_CI_BUILD_DIR: "real_work/work/build"
 
 .macos_arm64_xcode_ub:
-    extends: .macos_arm64
+    extends: .macos_tart
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_xcode_ub
@@ -134,7 +134,7 @@
         CMAKE_CI_NIGHTLY_IGNORE_DEPS: "true"
 
 .macos_arm64_ninja_multi:
-    extends: .macos_arm64
+    extends: .macos_tart
 
     variables:
         CMAKE_CONFIGURATION: macos_arm64_ninja_multi
@@ -168,28 +168,9 @@
 
 .macos_arm64_tags:
     tags:
-        - cmake # Since this is a bare runner, pin to a project.
+        - cmake
         - macos-arm64
-        - shell
-        - xcode-26.4
-        - nonconcurrent
-
-.macos_arm64_tags_ext:
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - macos-arm64
-        - shell
-        - xcode-26.4
-        - concurrent
-
-.macos_arm64_tags_package:
-    tags:
-        - cmake # Since this is a bare runner, pin to a project.
-        - macos-arm64
-        - shell
-        - xcode-26.4
-        - nonconcurrent
-        - finder
+        - tart
 
 ## macOS-specific scripts