release.yml: add tmate detached debugging to Mac job

Add a tmate session in detached mode to the Mac build job so that
one can SSH into the build agent while the pipeline steps run
concurrently. The setup step installs tmate via Homebrew, fetches
SSH public keys from the dscho and mjcheetham GitHub profiles to
restrict access, then starts tmate in detached mode and prints the
SSH connection string.

A final step with `condition: always()` waits for the tmate socket to
disappear, keeping the agent alive until the user disconnects. This
follows the pattern documented in the team's github-action-knowledge-
base.md for tmate detached mode inside containers, adapted for Azure
Pipelines syntax.

Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com>

Author: mjcheetham

.azure-pipelines/release.yml

@@ -713,6 +713,30 @@ extends:
                       # locking issues.
                       set -euo pipefail
                       sudo mdutil -i off / || true
+                - script: |
+                    # Install tmate
+                    brew install tmate
+
+                    # Fetch SSH public keys from GitHub profiles
+                    mkdir -p ~/.ssh &&
+                    curl -sf https://api.github.com/users/dscho/keys >/tmp/github-keys.json &&
+                    curl -sf https://api.github.com/users/mjcheetham/keys >>/tmp/github-keys.json &&
+                    sed -n 's/.*"key": "\(.*\)".*/\1/p' /tmp/github-keys.json >~/.ssh/authorized_keys &&
+                    test -s ~/.ssh/authorized_keys || {
+                      echo "ERROR: no SSH keys found for dscho or mjcheetham" >&2
+                      exit 1
+                    } &&
+
+                    # Generate an SSH key (needed for tmate)
+                    echo -e 'y\n' | ssh-keygen -q -t rsa -N '' -f ~/.ssh/id_rsa &&
+
+                    # Start tmate session in detached mode
+                    tmate -S /tmp/tmate.sock -a ~/.ssh/authorized_keys new-session -d &&
+                    tmate -S /tmp/tmate.sock wait tmate-ready &&
+
+                    # Print SSH invocation
+                    tmate -S /tmp/tmate.sock display -p '#{tmate_ssh}'
+                  displayName: 'Start tmate for debugging (detached)'
                 - task: Bash@3
                   displayName: 'Install build dependencies'
                   inputs:
@@ -744,6 +768,15 @@ extends:
                         -output libintl.a \
                         /usr/local/opt/gettext/lib/libintl.a \
                         /opt/homebrew/opt/gettext/lib/libintl.a
+                - script: |
+                    PATH="$HOME/bin:$PATH"
+                    while test -e /tmp/tmate.sock
+                    do
+                      tmate -S /tmp/tmate.sock display -p '#{tmate_ssh}'
+                      sleep 5
+                    done
+                  displayName: 'Wait for tmate session to end'
+                  condition: always()
                 - task: Bash@3
                   displayName: 'Configure universal build'
                   inputs: