ci: drop duplicate nightly-macos replay job (#1781 A2) (#1787)

The nightly-macos job in .github/workflows/replays-nightly.yml is
byte-identical in substance to smoke-macos in .github/workflows/macos.yml:
same setup-apple-runner-build call, same macos-helper gate, same
replay-macos gate invoked with --retries 2 --report-junit
test/artifacts/replays-macos.junit.xml. macos.yml already runs this gate
on every pull_request and every push to main, so the nightly copy adds no
additional information — 0/40 nightly runs have ever failed independently
of the PR/push gate.

Verified: check:gate-manifest and check:gate-manifest:test still pass
against the trimmed workflow (no gate lost its CI owner), and the full
check:tooling suite is green.

Author: thymikee

.github/workflows/replays-nightly.yml

@@ -276,48 +276,3 @@ jobs:
           artifact-name: replay-nightly-ios-artifacts
           agent-state-dir: ${{ env.AGENT_DEVICE_STATE_DIR }}
           runner-derived-path: ${{ env.AGENT_DEVICE_IOS_RUNNER_DERIVED_PATH }}
-
-  nightly-macos:
-    name: macOS Replay Suite
-    runs-on: macos-26
-    timeout-minutes: 80
-    env:
-      AGENT_DEVICE_STATE_DIR: ${{ github.workspace }}/.tmp/agent-device-state
-      AGENT_DEVICE_IOS_RUNNER_DERIVED_PATH: ${{ github.workspace }}/.tmp/macos-runner-derived
-    steps:
-      - name: Checkout
-        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-
-      - name: Setup toolchain
-        uses: ./.github/actions/setup-node-pnpm
-
-      - name: Restore and build macOS XCTest runner
-        uses: ./.github/actions/setup-apple-runner-build
-        with:
-          derived-path: ${{ env.AGENT_DEVICE_IOS_RUNNER_DERIVED_PATH }}
-          cache-key-prefix: macos-runner-prebuilt
-          gate: swift-runner-macos
-          xcuitest-platform: macos
-          xcuitest-destination: platform=macOS,arch=arm64
-
-      - name: Build macOS helper
-        uses: ./.github/actions/run-gate
-        with: { gate: macos-helper }
-
-      - name: Run macOS replay suite
-        uses: ./.github/actions/run-gate
-        with:
-          gate: replay-macos
-          args: |
-            --retries
-            2
-            --report-junit
-            test/artifacts/replays-macos.junit.xml
-
-      - name: Upload macOS artifacts
-        if: always()
-        uses: ./.github/actions/upload-agent-device-artifacts
-        with:
-          artifact-name: replay-nightly-macos-artifacts
-          agent-state-dir: ${{ env.AGENT_DEVICE_STATE_DIR }}
-          runner-derived-path: ${{ env.AGENT_DEVICE_IOS_RUNNER_DERIVED_PATH }}