feat(ci): use optimized deployment workflow in GitHub Actions

Update deploy-docs workflow to use the new justfile recipes that
implement version promotion. This enables safer deployments by
promoting tested preview versions instead of rebuilding.

Changes:
- Replace direct wrangler calls with justfile recipes
- Add GITHUB_ACTIONS, GITHUB_ACTOR, GITHUB_WORKFLOW env vars
- Preview: use just cf-deploy-preview
- Production: use just cf-deploy-production (auto-promotes if available)

Author: cameronraysmith

.github/workflows/deploy-docs.yaml

@@ -125,10 +125,14 @@ jobs:
         id: deployment
         env:
           SOPS_AGE_KEY: ${{ secrets.SOPS_AGE_KEY }}
+          GITHUB_ACTIONS: true
+          GITHUB_ACTOR: ${{ github.actor }}
+          GITHUB_WORKFLOW: ${{ github.workflow }}
         run: |
-          cd packages/docs
           if [ "${{ inputs.environment }}" = "preview" ]; then
-            nix develop -c sops exec-env ../../vars/shared.yaml "bunx wrangler versions upload --preview-alias b-${{ inputs.branch }}"
+            echo "Deploying preview for branch: ${{ inputs.branch }}"
+            nix develop -c just cf-deploy-preview ${{ inputs.branch }}
           else
-            nix develop -c sops exec-env ../../vars/shared.yaml "bunx wrangler deploy"
+            echo "Deploying to production (promoting existing version if available)"
+            nix develop -c just cf-deploy-production
           fi