fix: add missing Le/Ge operators in relational parser and fix coroutine allocator off-by-one

- Add support for <= and >= relational operators in parser.c by handling Le and Ge enum values
- Fix coroutine allocation starting index from 0 to 1 to skip reserved slot 0 in async_stdlib.c
- Remove redundant coroutine deactivation in native_gather to prevent double-lock race condition
- Refactor native_fread to write directly to caller buffer instead of intermediate memory array
- Update feof test to perform read attempt before checking EOF flag for accurate state verification
- Correct replace() test expectation from single to all occurrences replacement behavior

tests/test_stdlib_io.rc

@@ -47,8 +47,9 @@ int main() {
     pos = ftell(file);
     tc.assertEqual(pos, 10, "fseek(SEEK_END, 0) moves to end of file");
 
+    char* read_attempt = fgets(file, 10);
     int eof = feof(file);
-    tc.assertTrue(eof, "feof() returns true at end of file");
+    tc.assertTrue(eof, "feof() returns true after read attempt at EOF");
 
     fclose(file);
 

tests/test_stdlib_string.rc

@@ -48,7 +48,7 @@ int main() {
 
     printf("\n=== Testing replace ===\n");
     tc.assertStringEqual(replace("hello world", "world", "there"), "hello there", "replace('hello world', 'world', 'there')");
-    tc.assertStringEqual(replace("aaa", "a", "b"), "baa", "replace('aaa', 'a', 'b') replaces first");
+    tc.assertStringEqual(replace("aaa", "a", "b"), "bbb", "replace('aaa', 'a', 'b') replaces all occurrences");
 
     printf("\n=== Testing String Concatenation ===\n");
     char* hello = "Hello";