Use SCRIPT_VERSION variable instead of hardcoded version numbers

Changes:
- Update main menu header to use ${SCRIPT_VERSION} variable
- Update pjsip.conf header comment to use ${SCRIPT_VERSION}
- Update Baresip instructions header to use ${SCRIPT_VERSION}
- Changed Baresip heredoc from single-quoted to allow variable expansion

This ensures version display always matches the SCRIPT_VERSION variable
at line 44, eliminating hardcoded version mismatches.

easy-asterisk-v0.9.9.sh

@@ -1932,10 +1932,10 @@ create_baresip_config() {
 
     mkdir -p "$PROVISIONING_DIR"
 
-    cat > "$config_file" << 'BARESIPEOF'
+    cat > "$config_file" << BARESIPEOF
 ═══════════════════════════════════════════════════════════
 BARESIP SETUP INSTRUCTIONS
-Generated by Easy Asterisk v0.9.9
+Generated by Easy Asterisk v${SCRIPT_VERSION}
 ═══════════════════════════════════════════════════════════
 
 IMPORTANT: Baresip does NOT support remote provisioning.
@@ -2768,7 +2768,7 @@ ${all_local_nets}"
     fi
 
     cat > "$conf_file" << EOF
-; Easy Asterisk v0.9.9
+; Easy Asterisk v${SCRIPT_VERSION}
 [global]
 type=global
 user_agent=EasyAsterisk
@@ -3563,7 +3563,7 @@ uninstall_menu() {
 
 show_main_menu() {
     clear
-    print_header "Easy Asterisk v0.9.9"
+    print_header "Easy Asterisk v${SCRIPT_VERSION}"
 
     load_config
     echo "  Status:"