Priority-2: ENV Cache - Warm Path (FastCache/SuperSlab) getenv() 置換

変更内容:
- hakmem_env_cache.h: 2つの新ENV変数を追加
  (TINY_FAST_STATS, TINY_UNIFIED_CACHE)
- tiny_fastcache.c: 2箇所の getenv() を置換
  (TINY_PROFILE, TINY_FAST_STATS)
- tiny_fastcache.h: 1箇所の getenv() を置換
  (TINY_PROFILE in inline function)
- superslab_slab.c: 1箇所の getenv() を置換
  (TINY_SLL_DIAG)
- tiny_unified_cache.c: 1箇所の getenv() を置換
  (TINY_UNIFIED_CACHE)

効果: Warm path層からも syscall を排除 (ENV変数数: 28→30)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

core/front/tiny_unified_cache.c

@@ -8,6 +8,7 @@
 #include "../superslab/superslab_inline.h"   // Phase 23-E: ss_active_add, slab_index_for, ss_slabs_capacity
 #include "../hakmem_super_registry.h"        // For hak_super_lookup (pointer→SuperSlab)
 #include "../box/pagefault_telemetry_box.h"  // Phase 24: Box PageFaultTelemetry (Tiny page touch stats)
+#include "../hakmem_env_cache.h"             // Priority-2: ENV cache (eliminate syscalls)
 #include <stdlib.h>
 #include <string.h>
 
@@ -37,10 +38,10 @@ __thread uint64_t g_unified_cache_full[TINY_NUM_CLASSES] = {0};
 
 // Enable flag (default: ON, disable with HAKMEM_TINY_UNIFIED_CACHE=0)
 int unified_cache_enabled(void) {
+    // Priority-2: Use cached ENV (eliminate lazy-init static overhead)
     static int g_enable = -1;
     if (__builtin_expect(g_enable == -1, 0)) {
-        const char* e = getenv("HAKMEM_TINY_UNIFIED_CACHE");
-        g_enable = (e && *e && *e == '0') ? 0 : 1;  // default ON
+        g_enable = HAK_ENV_TINY_UNIFIED_CACHE();
 #if !HAKMEM_BUILD_RELEASE
         if (g_enable) {
             fprintf(stderr, "[Unified-INIT] unified_cache_enabled() = %d\n", g_enable);