Display SSH completion candidates for ambiguous prefixes

src/console_completion.h

@@ -22,6 +22,15 @@ void console_completion_visit(const char *line,
 /* Bounded longest-prefix completion shared by the UART and admin SSH frontends. */
 bool console_completion_expand(const char *line, char *completed, size_t capacity);
 
+/*
+ * Format the matching candidates as CRLF-terminated lines for a frontend that
+ * cannot use linenoise's native completion display. A successful empty result
+ * means no candidate matched; false means the supplied output buffer was too
+ * small or an argument was invalid.
+ */
+bool console_completion_format_matches(const char *line, char *output, size_t capacity,
+                                       size_t *output_length);
+
 #ifdef __cplusplus
 }
 #endif