Add Piler email archiving support and update scripts

Introduces Piler email archiving with new install and container scripts, and adds metadata for frontend integration. Updates Pixelfed and Postgresus install scripts to improve PHP-FPM pool configuration and streamline build steps.

install/postgresus-install.sh

@@ -26,16 +26,13 @@ NODE_VERSION="24" setup_nodejs
 fetch_and_deploy_gh_release "postgresus" "RostislavDugin/postgresus" "tarball" "latest" "/opt/postgresus"
 
 msg_info "Building Postgresus (Patience)"
-# Build frontend
 cd /opt/postgresus/frontend
 $STD npm ci
 $STD npm run build
-
-# Build backend
 cd /opt/postgresus/backend
 $STD go mod tidy
 $STD go mod download
-$STD CGO_ENABLED=0 go build -o /opt/postgresus/postgresus ./cmd/main.go
+CGO_ENABLED=0 go build -o postgresus .
 mkdir -p /opt/postgresus/{data,backups,logs}
 cp -r /opt/postgresus/frontend/dist /opt/postgresus/ui
 cp -r /opt/postgresus/backend/migrations /opt/postgresus/