fix(migrate): Use python3-psycopg2 + system-site-packages for barman

The postgres:16 image lacks gcc / libpq-dev, so pip build of barman's
psycopg2 dep fails. Install the compiled binary via apt and point the
venv at system site-packages so barman[cloud] reuses it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.woodpecker/migrate-authentik-db.yml

@@ -71,8 +71,11 @@ steps:
       - set -euo pipefail
       - export DEBIAN_FRONTEND=noninteractive
       - apt-get update -qq
-      - apt-get install -y --no-install-recommends python3 python3-pip python3-venv awscli ca-certificates >/dev/null
-      - python3 -m venv /opt/barman
+      # python3-psycopg2 provides the compiled binary so barman's pip
+      # install doesn't try to build psycopg2 from source (postgres:16
+      # ships without gcc / libpq-dev).
+      - apt-get install -y --no-install-recommends python3 python3-pip python3-venv python3-psycopg2 awscli ca-certificates >/dev/null
+      - python3 -m venv --system-site-packages /opt/barman
       - /opt/barman/bin/pip install --no-cache-dir --quiet 'barman[cloud,aws-snapshots]'
       - export PATH="/opt/barman/bin:$PATH"
       # Wait for the ephemeral Postgres service to come up

.woodpecker/migrate-paperless.yml

@@ -77,8 +77,10 @@ steps:
       - set -euo pipefail
       - export DEBIAN_FRONTEND=noninteractive
       - apt-get update -qq
-      - apt-get install -y --no-install-recommends python3 python3-pip python3-venv awscli ca-certificates >/dev/null
-      - python3 -m venv /opt/barman
+      # python3-psycopg2 provides the compiled binary so barman's pip
+      # install doesn't try to build psycopg2 from source.
+      - apt-get install -y --no-install-recommends python3 python3-pip python3-venv python3-psycopg2 awscli ca-certificates >/dev/null
+      - python3 -m venv --system-site-packages /opt/barman
       - /opt/barman/bin/pip install --no-cache-dir --quiet 'barman[cloud,aws-snapshots]'
       - export PATH="/opt/barman/bin:$PATH"
       - |