feat: Add ACE allocation failure tracing and debug hooks

This commit introduces a comprehensive tracing mechanism for allocation failures within the Adaptive Cache Engine (ACE) component. This feature allows for precise identification of the root cause for Out-Of-Memory (OOM) issues related to ACE allocations.

Key changes include:
- **ACE Tracing Implementation**:
  - Added  environment variable to enable/disable detailed logging of allocation failures.
  - Instrumented , , and  to distinguish between "Threshold" (size class mismatch), "Exhaustion" (pool depletion), and "MapFail" (OS memory allocation failure).
- **Build System Fixes**:
  - Corrected  to ensure  is properly linked into , resolving an  error.
- **LD_PRELOAD Wrapper Adjustments**:
  - Investigated and understood the  wrapper's behavior under , particularly its interaction with  and  checks.
  - Enabled debugging flags for  environment to prevent unintended fallbacks to 's  for non-tiny allocations, allowing comprehensive testing of the  allocator.
- **Debugging & Verification**:
  - Introduced temporary verbose logging to pinpoint execution flow issues within  interception and  routing. These temporary logs have been removed.
  - Created  to facilitate testing of the tracing features.

This feature will significantly aid in diagnosing and resolving allocation-related OOM issues in  by providing clear insights into the failure pathways.

core/box/hak_core_init.inc.h

@@ -200,7 +200,10 @@ static void hak_init_impl(void) {
     // Phase 7.4: Cache HAKMEM_INVALID_FREE to eliminate 44% CPU overhead
     // Perf showed getenv() on hot path consumed 43.96% CPU time (26.41% strcmp + 17.55% getenv)
     char* inv = getenv("HAKMEM_INVALID_FREE");
-    if (inv && strcmp(inv, "fallback") == 0) {
+    if (inv && strcmp(inv, "skip") == 0) {
+        g_invalid_free_mode = 1;  // explicit opt-in to legacy skip mode
+        HAKMEM_LOG("Invalid free mode: skip check (HAKMEM_INVALID_FREE=skip)\n");
+    } else if (inv && strcmp(inv, "fallback") == 0) {
         g_invalid_free_mode = 0;  // fallback mode: route invalid frees to libc
         HAKMEM_LOG("Invalid free mode: fallback to libc (HAKMEM_INVALID_FREE=fallback)\n");
     } else {
@@ -211,8 +214,9 @@ static void hak_init_impl(void) {
             g_invalid_free_mode = 0;
             HAKMEM_LOG("Invalid free mode: fallback to libc (auto under LD_PRELOAD)\n");
         } else {
-            g_invalid_free_mode = 1;  // default: skip invalid-free check
-            HAKMEM_LOG("Invalid free mode: skip check (default)\n");
+            // Default: safety first (fallback), avoids routing unknown pointers into Tiny
+            g_invalid_free_mode = 0;
+            HAKMEM_LOG("Invalid free mode: fallback to libc (default)\n");
         }
     }