chore: point install/update/self-update at this fork instead of upstream

install.sh, update.sh, and x-ui.sh all hardcoded MHSanaei/3x-ui as the
release/raw-file source (release tarball downloads, the self-update
script fetch, service unit fallback downloads). Left as-is, merging
AmneziaWG into main and cutting a release here would still silently
install upstream's stock binary — none of our work would ever reach a
machine that runs the curl-from-GitHub one-liner.

Repointed all of it at Kuzz007/3x-ui, plus two more functional (not
just doc/attribution) spots the same grep turned up: the panel's own
in-app update checker (internal/web/service/panel/panel.go's
panelUpdaterURL and the GitHub releases API calls in
fetchPanelRelease) and deploy/cloud-init/cloud-init.yaml's
auto-provisioning curl line. Left README/docs/CONTRIBUTING/FUNDING
attribution to the upstream project untouched — this is still a fork
of MHSanaei's work, that credit stays.

Third-party dependency downloads in .github/workflows/release.yml
(Xray-core, geoip/geosite data, mtg-multi) intentionally still point
at their own respective upstream projects, not this fork.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

deploy/cloud-init/cloud-init.yaml

@@ -44,7 +44,7 @@ write_files:
       #   export XUI_DB_DSN="postgres://user:pass@host:5432/db?sslmode=disable"
       # ------------------------------------------------------------------------
 
-      curl -fsSL https://raw.githubusercontent.com/MHSanaei/3x-ui/main/install.sh | bash
+      curl -fsSL https://raw.githubusercontent.com/Kuzz007/3x-ui/main/install.sh | bash
 
       # Surface the generated credentials. Full creds (incl. password + API token)
       # go ONLY to the serial console (/dev/console, owner-only). /etc/motd is