fix: demo not→! in code_gen_loop and self_improving_agent

code_gen_loop.omc: `if not run_result["ok"]` → `if !run_result["ok"]`
self_improving_agent.omc: two `if not x` → `if !x` (run/test checks)

substrate_rag.omc and recursive_improve.omc verified clean (no fixes).
All four demos parse and execute correctly up to first llm_call boundary.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: RandomCoder-lab

examples/demos/code_gen_loop.omc

@@ -82,7 +82,7 @@ fn code_gen_loop(task_description, eval_prompt_template, generations) {
         # Try to run it
         h run_result = safe_run(current_code, "")
         h run_status = "ok"
-        if not run_result["ok"] { run_status = to_str(run_result["error"]) }
+        if !run_result["ok"] { run_status = to_str(run_result["error"]) }
         print(str_concat("  Run status: ", run_status))
 
         arr_push(history, {

examples/demos/self_improving_agent.omc

@@ -47,7 +47,7 @@ fn run_test(code, test_case) {
         "__test_result"
     )
     h result = safe_eval(full_code)
-    if not result["ok"] {
+    if !result["ok"] {
         return {passed: false, error: result["error"], expected: test_case["expected"], got: null}
     }
     h passed = result["value"] == test_case["expected"]
@@ -59,7 +59,7 @@ fn run_all_tests(code, tests) {
     h i = 0
     while i < arr_len(tests) {
         h r = run_test(code, tests[i])
-        if not r["passed"] {
+        if !r["passed"] {
             arr_push(failures, {
                 test_idx: i,
                 expected: r["expected"],