feat(install): ask for the public URL, wire it into .env

install.sh now asks one question on fresh installs — the URL the app is
opened on. Accepts https://primora.example.com (TLS at the user's proxy),
primora.example.com, or 192.168.1.50:8085; the port becomes NGINX_PORT.
The answer rewrites every public URL var and COOKIE_DOMAIN for real DNS
names. PUBLIC_URL env keeps it non-interactive; legacy DOMAIN/NGINX_PORT
still work; reruns over an existing .env skip the question and display
the URL from the file.

Also trust both URL schemes on the serving host in trustedOrigins —
external TLS termination makes nginx report http while browsers arrive
over https.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

README.md

@@ -77,7 +77,9 @@ Prerequisites: Docker with the Compose plugin.
 curl -fsSL https://raw.githubusercontent.com/Dvorinka/Primora/master/install.sh | bash
 ```
 
-Installs into `./primora`, generates secrets, and starts the stack on port 80.
+Installs into `./primora`, asks one question — the URL you'll open the app on
+(domain, IP, optional port) — generates secrets, and starts the stack.
+Non-interactive: `PUBLIC_URL=https://primora.example.com bash install.sh`.
 Or from a clone:
 
 ```bash