feat: only run all seeds on first startup

CODE_GUIDELINES.md

@@ -284,13 +284,13 @@ end
 
 ### 1.2.1 Database Seeds
 
-Seeds are split into **bootstrap** and **dev**:
+Seeds are split into **bootstrap** and **dev**. They run on every start (e.g. `just run`, Docker entrypoint) but **exit early** if already applied so startup stays fast and no duplicate data is created.
 
-- **`priv/repo/seeds.exs`** – Entrypoint. Runs `seeds_bootstrap.exs` always; runs `seeds_dev.exs` only when `Mix.env()` is `:dev` or `:test`.
+- **`priv/repo/seeds.exs`** – Entrypoint. If the admin user (ADMIN_EMAIL or default) already exists, skips entirely; otherwise runs `seeds_bootstrap.exs` and, in dev/test, `seeds_dev.exs`.
 - **`priv/repo/seeds_bootstrap.exs`** – Creates only data required for system startup: membership fee types, custom fields, roles, admin user, system user, global settings (including default membership fee type). No members, no groups. Used in all environments (dev, test, prod).
 - **`priv/repo/seeds_dev.exs`** – Creates 20 sample members, groups, and optional custom field values. Run only in dev and test.
 
-In production, running `mix run priv/repo/seeds.exs` executes only the bootstrap part (no dev seeds).
+In production, running `mix run priv/repo/seeds.exs` (or `Mv.Release.run_seeds/0`) executes only the bootstrap part when not yet applied (no dev seeds unless `RUN_DEV_SEEDS=true`). The “already applied” check uses `Mv.Release.bootstrap_seeds_applied?/0` (admin user exists).
 
 ### 1.3 Domain-Driven Design