Phase 4b: Add master debug control (HAKMEM_DEBUG_ALL/LEVEL)

Add centralized debug control system that allows enabling all debug
modules at once, while maintaining backwards compatibility with
individual module ENVs.

New file: core/hakmem_debug_master.h
- HAKMEM_DEBUG_ALL=1: Enable all debug modules
- HAKMEM_DEBUG_LEVEL=N: Set debug level (0=off, 1=critical, 2=normal, 3=verbose)
- HAKMEM_QUIET=1: Suppress all debug (highest priority)
- hak_debug_check(): Check if module should enable debug
- hak_is_quiet(): Quick check for quiet mode

Priority order:
1. HAKMEM_QUIET=1 → suppress all
2. Specific module ENV (e.g., HAKMEM_SFC_DEBUG=1)
3. HAKMEM_DEBUG_ALL=1
4. HAKMEM_DEBUG_LEVEL >= threshold

Updated files:
- core/hakmem_elo.c: Use hak_is_quiet() instead of local implementation
- core/hakmem_shared_pool.c: Use hak_debug_check() for lock stats

Performance: No regression (71.5M ops/s maintained)

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

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

core/hakmem_shared_pool.c

@@ -1,6 +1,7 @@
 #include "hakmem_shared_pool.h"
 #include "hakmem_tiny_superslab.h"
 #include "hakmem_tiny_superslab_constants.h"
+#include "hakmem_debug_master.h"  // Phase 4b: Master debug control
 #include "box/ss_slab_meta_box.h"  // Phase 3d-A: SlabMeta Box boundary
 #include "box/ss_hot_cold_box.h"   // Phase 12-1.1: EMPTY slab marking
 #include "box/pagefault_telemetry_box.h"  // Box PageFaultTelemetry (PF_BUCKET_SS_META)
@@ -25,10 +26,10 @@ static int g_lock_stats_enabled = -1;                  // -1=uninitialized, 0=of
 
 #if !HAKMEM_BUILD_RELEASE
 // Initialize lock stats from environment variable
+// Phase 4b: Now uses hak_debug_check() for master debug control support
 static inline void lock_stats_init(void) {
     if (__builtin_expect(g_lock_stats_enabled == -1, 0)) {
-        const char* env = getenv("HAKMEM_SHARED_POOL_LOCK_STATS");
-        g_lock_stats_enabled = (env && *env && *env != '0') ? 1 : 0;
+        g_lock_stats_enabled = hak_debug_check("HAKMEM_SHARED_POOL_LOCK_STATS");
     }
 }