ci: fresh-install macOS lane on macos-14 (support floor); workspace mcpp -> 0.0.51

Author: Sunrisepeak

.github/workflows/ci-fresh-install.yml

@@ -112,7 +112,10 @@ jobs:
   # ──────────────────────────────────────────────────────────────────
   macos-fresh:
     name: macOS fresh install
-    runs-on: macos-15
+    # macos-14: the support floor (mcpp ≥0.0.50 / xlings ≥0.4.50 ship
+    # minos=14.0 static-libc++ binaries). A fresh install passing here
+    # is the continuous proof of the macOS 14 floor.
+    runs-on: macos-14
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
@@ -121,7 +124,9 @@ jobs:
         env:
           XLINGS_NON_INTERACTIVE: '1'
         run: |
-          curl -fsSL https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_install.sh | bash -s v0.4.38
+          # v0.4.50+: first xlings release whose macosx binary runs on
+          # macOS 14 (older ones carry minos=15 and refuse to start).
+          curl -fsSL https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_install.sh | bash -s v0.4.50
           echo "$HOME/.xlings/subos/current/bin" >> "$GITHUB_PATH"
 
       - name: Install mcpp and config mirror

.xlings.json

@@ -1,5 +1,5 @@
 {
   "workspace": {
-    "mcpp": "0.0.20"
+    "mcpp": "0.0.51"
   }
 }