Use the certs/ fallback in every environment

TLS no longer depends on NODE_ENV: the TLS_* variables win, else certs/
is used whenever it exists (the container's /app/certs mount lands there
too), and TLS_DISABLED=1 is the only way to serve plain HTTP with a
certificate present. The plain-HTTP redirect listener now starts whenever
TLS is on, not only in development, and HTTP_REDIRECT_PORT replaces
DEV_HTTP_PORT. The installer writes TLS_DISABLED=1 for --no-https, and the
health check follows the same rule.

src/functions/server/start-http-redirect.ts

@@ -8,18 +8,19 @@ type Params = {
 };
 
 /**
- * Development convenience: a plain-HTTP listener on the port above the
- * HTTPS one, which sends the browser to the same page over HTTPS.
+ * A plain-HTTP listener on the port above the HTTPS one, which sends the
+ * browser to the same page over HTTPS.
  *
  * A port that speaks TLS cannot answer plain HTTP, so this cannot sit on
  * the HTTPS port itself: `http://<host>:<port>` still fails, but
- * `http://<host>:<port + 1>` lands on the right page. `DEV_HTTP_PORT`
- * picks another port. Production does not start it (only one port is
- * published, and it is HTTPS).
+ * `http://<host>:<port + 1>` lands on the right page. `HTTP_REDIRECT_PORT`
+ * picks another port. Every environment starts it; the container publishes
+ * only the HTTPS port, so there it is reachable only if that second port is
+ * published too.
  */
 export default function startHttpRedirect({ https_port }: Params) {
     const base = Number(https_port);
-    const configured = Number(process.env.DEV_HTTP_PORT);
+    const configured = Number(process.env.HTTP_REDIRECT_PORT);
     const redirect_port =
         Number.isInteger(configured) && configured > 0
             ? configured