fix(xmpp): obfuscate client identity in protocol exchanges

Modify version responses to return a generic client name and omit
version strings. Drop the "profanity." prefix from dynamically
generated JID resources. Spoof the XEP-0115 capabilities node URI to
prevent service discovery/presence fingerprinting. These adjustments
reduce the client's attack surface by minimizing identifiable metadata.

src/config/preferences.c

@@ -2689,7 +2689,6 @@ _get_default_boolean(preference_t pref)
     case PREF_STATUSBAR_SHOW_NUMBER:
     case PREF_STATUSBAR_SHOW_READ:
     case PREF_STATUSBAR_SHOW_DBBACKEND:
-    case PREF_REVEAL_OS:
     case PREF_CORRECTION_ALLOW:
     case PREF_RECEIPTS_SEND:
     case PREF_CARBONS:
@@ -2704,6 +2703,7 @@ _get_default_boolean(preference_t pref)
     case PREF_STROPHE_SM_RESEND:
     case PREF_AUTOPING_WARNING:
         return TRUE;
+    case PREF_REVEAL_OS:
     case PREF_SPELLCHECK_ENABLE:
     case PREF_PGP_PUBKEY_AUTOIMPORT:
     case PREF_FORCE_ENCRYPTION: