chore: phase 0 reproducible docker/dev setup with version pinning

.env.example

@@ -1,10 +1,15 @@
 # Copy to `.env` and fill in values. `.env` is gitignored.
-# It holds only ubiquitous variables (identical value in dev and prod).
-# Dev-only variables travel via devcontainer.json `containerEnv`
-# (e.g. APP_ENV=dev); paths resolve from the repo root in code.
+# Dev defaults live in docker-compose.yml (APP_ENV=dev, FORGEJO_USERNAME=jonas).
+# Prod overrides via this .env file (e.g. APP_ENV=prod).
+# Paths resolve from the repo root in code.
 FORGEJO_TOKEN=
 
-# --- langflow (authoring UI) ---
+# --- langflow (authoring UI) + lfx (flow runtime): pinned in lockstep ---
+# LFX contract: major.minor of Langflow and LFX must match (patches are
+# independent). Bump deliberately on both sides together (compose image pin
+# below + Dockerfile.lfx ARG + backend dev dep `lfx~=`), then re-check
+# backend/flows/*.json with `lfx upgrade --upgrade-flow=safe`.
+LANGFLOW_VERSION=1.12.0
 LANGFLOW_URL=http://langflow:7860
 LANGFLOW_SUPERUSER=langflow
 LANGFLOW_SUPERUSER_PASSWORD=
@@ -23,5 +28,18 @@ CALLBACK_BASE_URL=http://api:8000
 # --- frontend mode: dev server with HMR (prod .env must set `preview`) ---
 FRONTEND_MODE=dev
 
+# --- access management (request + approval, invite via email) ---
+# Public frontend URL (magic links point here).
+FRONTEND_URL=http://localhost:3000
+# Comma-separated emails that become admins (role assignment + bootstrap).
+ADMIN_EMAILS=
+# Reply-To on outgoing mail; also receives new access-request notifications.
+CONTACT_TO=
+MAIL_FROM=
+SMTP_HOST=
+SMTP_PORT=587
+SMTP_USERNAME=
+SMTP_PASSWORD=
+
 # --- LLM (optional; tests mock the provider without it) ---
 # LLM_API_KEY=