rebrand: remove GitHub/alleyviper references, position as Weboria enterprise product

README rewritten with the "ARGUS Enterprise Web Security Platform" positioning
and full feature list. install.sh/update.sh now fetch deployment files from
this Gitea repo (git-cloud.weboria.eu) instead of raw.githubusercontent.com,
default install directory changed to /opt/argus, next-steps messaging aligned
with the full onboarding journey (first-run wizard, proxy hosts, ANIS, policy
center). Support link changed from GitHub Issues to the Weboria Support
Portal.

Deliberately NOT changed: docker-compose.yml's image: lines still pull from
ghcr.io — Weboria's own private registry (registry.weboria.eu) resolves in
DNS but has no registry service listening yet (confirmed via direct check),
so switching now would break every real install. Both README and install.sh
document this as a known, tracked gap rather than silently pointing at
infrastructure that doesn't work. Same treatment for license-key validation
during install — not implemented, since there's no licensing service to
validate against yet.

update.sh

@@ -1,14 +1,15 @@
 #!/usr/bin/env bash
 #
-# ARGUS updater — pulls the latest published images and restarts the stack.
+# ARGUS Enterprise Web Security Platform — updater. Pulls the latest
+# published images and restarts the stack.
 #
-#   cd ~/argus && ./update.sh
+#   cd /opt/argus && ./update.sh
 #   (or, if you don't have it locally yet)
-#   curl -fsSL https://raw.githubusercontent.com/alleyviper/argus/main/update.sh | bash
+#   curl -fsSL https://git-cloud.weboria.eu/weboria/argus-installer/raw/branch/main/update.sh | bash
 #
 set -euo pipefail
 
-INSTALL_DIR="${ARGUS_INSTALL_DIR:-$HOME/argus}"
+INSTALL_DIR="${ARGUS_INSTALL_DIR:-/opt/argus}"
 
 bold()  { printf '\033[1m%s\033[0m\n' "$1"; }
 info()  { printf '  %s\n' "$1"; }