feat: add backup files for rlib core modules including arena, nsock, and autocomplete

Introduces initial backup snapshots of core rlib components: arena allocator with construct/new/alloc/free/reset API, nsock network socket wrapper with select-based event loop, autocomplete string list implementation, argument parser utilities, and main dispatcher for httpd/rmerge/rcov/rcase tools. Includes MIT license header and rlib.h umbrella include with 30+ submodule headers.

.backup.1.rbuffer.c

@@ -0,0 +1,39 @@
+#include "rtest.h"
+#include "rbuffer.h"
+
+int main() {
+    rtest_banner("rbuffer");
+    unsigned char *content = (unsigned char *)"[   {\n\t \"\r1\t3\n4truefalsetrue \" }, ]";
+    char *ignore = "\r| |\n|\t|\f|\v";
+    rbuffer_t *buffer = rbuffer_new(content, ustrlen(content));
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '[');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '{');
+    rbuffer_reset(buffer);
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '[');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '{');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '"');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '1');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '3');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '4');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == 't');
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == 'f');
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == 't');
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    rbuffer_pop(buffer);
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == '"');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b|}", ignore) == '}');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b", ignore) == ',');
+    assert(*rbuffer_consume(buffer, "{|[|,|\"|\\d|\\b|]", ignore) == ']');
+    unsigned char *str = rbuffer_to_string(buffer);
+    printf(">%s<\n", str);
+    free(str);
+    return rtest_end("");
+}