chore: add a temporary Vercel credential probe

Author: rynfar

.github/workflows/vercel-probe.yml

@@ -0,0 +1,48 @@
+name: Vercel credential probe
+
+# Temporary diagnostic. The hosted web deploy fails with "User not found (404)"
+# and each retry costs a full four-platform build, so this exercises the token
+# on its own. Delete once the deploy is green.
+on:
+  workflow_dispatch:
+
+jobs:
+  probe:
+    runs-on: blacksmith-8vcpu-ubuntu-2404
+    timeout-minutes: 5
+    env:
+      VERCEL_TOKEN: ${{ secrets.VERCEL_TOKEN }}
+      VERCEL_ORG_ID: ${{ secrets.VERCEL_ORG_ID }}
+      VERCEL_PROJECT_ID: ${{ secrets.VERCEL_PROJECT_ID }}
+      VERCEL_TEAM_SLUG: ${{ vars.VERCEL_TEAM_SLUG }}
+    steps:
+      - name: Probe token
+        shell: bash
+        run: |
+          set -uo pipefail
+          echo "token length: ${#VERCEL_TOKEN}"
+          echo "org id: $VERCEL_ORG_ID"
+          echo "team slug: ${VERCEL_TEAM_SLUG:-<unset>}"
+
+          echo "--- 1. whoami (no scope) ---"
+          npx --yes vercel@53.1.1 whoami --token "$VERCEL_TOKEN" 2>&1 | tail -3
+
+          echo "--- 2. project ls, scope = team slug ---"
+          npx --yes vercel@53.1.1 project ls --token "$VERCEL_TOKEN" \
+            --scope "${VERCEL_TEAM_SLUG}" 2>&1 | tail -5
+
+          echo "--- 3. project ls, scope = org id ---"
+          npx --yes vercel@53.1.1 project ls --token "$VERCEL_TOKEN" \
+            --scope "$VERCEL_ORG_ID" 2>&1 | tail -5
+
+          echo "--- 4. project ls, no scope (env vars only) ---"
+          npx --yes vercel@53.1.1 project ls --token "$VERCEL_TOKEN" 2>&1 | tail -5
+
+          echo "--- 5. raw API: /v2/user ---"
+          curl -sS -o /dev/null -w "  /v2/user -> %{http_code}\n" \
+            -H "Authorization: Bearer $VERCEL_TOKEN" https://api.vercel.com/v2/user
+
+          echo "--- 6. raw API: project by id, scoped to team ---"
+          curl -sS -o /dev/null -w "  /v9/projects -> %{http_code}\n" \
+            -H "Authorization: Bearer $VERCEL_TOKEN" \
+            "https://api.vercel.com/v9/projects/${VERCEL_PROJECT_ID}?teamId=${VERCEL_ORG_ID}"