Fix federation signature handling and IP guard (#276)

* Fix federation signature handling and IP guard

* Avoid defaulting isPrivate before signature verification

* Normalize instance domain host handling for restricted IP check

* ignore web app credentials

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Co-authored-by: l5yth <d220195275+l5yth@users.noreply.github.com>

.gitignore

@@ -66,3 +66,6 @@ reports/
 # AI planning and documentation
 ai_docs/
 *.log
+
+# Generated credentials for the instance
+web/.config