Move macOS build to a manual-only workflow

Gitea evaluates a job's `if` on the runner, so with no macOS runner the
gated job sat queued forever and kept every run in progress. Make it a
separate workflow_dispatch-only workflow until a macOS runner exists.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.gitea/workflows/check.yaml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   # Runs on the existing Linux runners. Wakeful links AppKit, IOKit and Carbon,
-  # so this can parse the Swift but not compile it; see the macos job below.
+  # so this can parse the Swift but not compile it; see macos.yaml.
   lint:
     runs-on: ubuntu-latest
     container:
@@ -27,22 +27,3 @@ jobs:
 
       - name: Check
         run: scripts/check.sh
-
-  # A real build. Off until a macOS act_runner with the "macos" label is
-  # registered; then set the repo variable MACOS_RUNNER=true to enable it.
-  macos:
-    if: vars.MACOS_RUNNER == 'true'
-    runs-on: macos
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Check
-        run: scripts/check.sh
-
-      - name: Build (warnings are errors)
-        run: swift build -c release -Xswiftc -warnings-as-errors
-
-      - name: Bundle and ad-hoc sign
-        run: |
-          make bundle
-          plutil -lint dist/Wakeful.app/Contents/Info.plist