fix: load ./.env only when private and owned, add --env-file and AEGIS_ENV_FILE (SEC-04)

README.md

@@ -63,7 +63,9 @@ uv run aegis-gitea-mcp setup
   they are missing, and keeping values it does not know;
 - prints ready-made client configurations and a docker-compose snippet.
 
-Secrets are only ever written to the env file, never printed.
+Secrets are only ever written to the env file, never printed. `serve` reads `./.env` only
+while it keeps the 0600 mode and your ownership; to keep the file elsewhere use
+`--env-file PATH` (or `AEGIS_ENV_FILE`) on both commands.
 
 Run it:
 
@@ -247,8 +249,10 @@ More in [docs/deployment.md](docs/deployment.md) and [docs/hardening.md](docs/ha
 
 ## Configuration
 
-All settings are environment variables (or `.env` in the working directory), case-insensitive.
-Core ones:
+All settings are environment variables (or an env file), case-insensitive. The env file is
+`--env-file PATH`, else `AEGIS_ENV_FILE`, else `./.env` only when it is a regular file owned by
+you with mode 0600 (what `setup` writes); any other `./.env` is ignored with a warning (run
+`chmod 600 .env` or pass `--env-file`). Real environment variables always win. Core ones:
 
 | Variable | Default | Meaning |
 |---|---|---|