chore(docker): improve base image and organize docker files

- Add wget, ripgrep, python3, and GitHub CLI (gh) to base image
- Add OPENCODE_ALLOW_ALL_MODELS=true to production ENV
- Move compose files, onboard-smoke Dockerfile to docker/
- Move entrypoint script to scripts/docker-entrypoint.sh
- Add Podman Quadlet unit files (pod, app, db containers)
- Add docker/README.md with build, compose, and quadlet docs
- Add scripts/docker-build-test.sh for local build validation
- Update all doc references for new file locations
- Keep main Dockerfile at project root (no .dockerignore changes needed)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/docker-entrypoint.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+set -e
+
+# Capture runtime UID/GID from environment variables, defaulting to 1000
+PUID=${USER_UID:-1000}
+PGID=${USER_GID:-1000}
+
+# Adjust the node user's UID/GID if they differ from the runtime request
+# and fix volume ownership only when a remap is needed
+changed=0
+
+if [ "$(id -u node)" -ne "$PUID" ]; then
+    echo "Updating node UID to $PUID"
+    usermod -o -u "$PUID" node
+    changed=1
+fi
+
+if [ "$(id -g node)" -ne "$PGID" ]; then
+    echo "Updating node GID to $PGID"
+    groupmod -o -g "$PGID" node
+    usermod -g "$PGID" node
+    changed=1
+fi
+
+if [ "$changed" = "1" ]; then
+    chown -R node:node /paperclip
+fi
+
+exec gosu node "$@"