refactor: rename materia → beanflows throughout codebase

- Rename src/materia/ → src/beanflows/ (Python package)
- Rename transform/sqlmesh_materia/ → transform/sqlmesh_beanflows/
- Rename infra/supervisor/materia-supervisor.service → beanflows-supervisor.service
- Rename infra/backup/materia-backup.{service,timer} → beanflows-backup.{service,timer}
- Update all path strings: /opt/materia → /opt/beanflows, /data/materia → /data/beanflows
- Update pyproject.toml: project name, CLI entrypoint, workspace source key
- Update all internal imports from materia.* → beanflows.*
- Update infra scripts: REPO_DIR, service names, systemctl references
- Fix docker-compose.prod.yml: /data/materia → /data/beanflows (bind mount path)

Intentionally left unchanged: Pulumi stack name (materia-infrastructure) and
Hetzner resource names ("materia-key", "managed_by: materia") — these reference
live cloud infrastructure and require separate cloud-side renames.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

infra/setup_server.sh

@@ -8,7 +8,7 @@
 #
 # What it does:
 #   1. Creates beanflows_service user (nologin) + adds to docker group
-#   2. Creates /opt/materia + /data/materia/landing with correct ownership
+#   2. Creates /opt/beanflows + /data/beanflows/landing with correct ownership
 #   3. Installs git, curl, age, sops, rclone, uv
 #   4. Generates ed25519 SSH deploy key for GitLab read access
 #   5. Generates age keypair at ~/.config/sops/age/keys.txt (as service user)
@@ -17,10 +17,10 @@
 set -euo pipefail
 
 SERVICE_USER="beanflows_service"
-APP_DIR="/opt/materia"
-DATA_DIR="/data/materia"
+APP_DIR="/opt/beanflows"
+DATA_DIR="/data/beanflows"
 SSH_DIR="/home/${SERVICE_USER}/.ssh"
-DEPLOY_KEY="${SSH_DIR}/materia_deploy"
+DEPLOY_KEY="${SSH_DIR}/beanflows_deploy"
 SOPS_AGE_DIR="/home/${SERVICE_USER}/.config/sops/age"
 
 ROTATE_KEYS="${ROTATE_KEYS:-}"
@@ -63,7 +63,7 @@ fi
 
 if [ ! -f "${DEPLOY_KEY}" ]; then
     sudo -u "${SERVICE_USER}" ssh-keygen -t ed25519 \
-        -f "${DEPLOY_KEY}" -N "" -C "materia-deploy"
+        -f "${DEPLOY_KEY}" -N "" -C "beanflows-deploy"
 fi
 
 if [ ! -f "${SSH_DIR}/config" ]; then