Fix: Add missing superslab_allocate() declaration

Root cause identified by Task agent investigation:
- superslab_allocate() called without declaration in 2 files
- Compiler assumes implicit int return type (C99 standard)
- Actual signature returns SuperSlab* (64-bit pointer)
- Pointer truncated to 32-bit int, then sign-extended to 64-bit
- Results in corrupted pointer and segmentation fault

Mechanism of corruption:
1. superslab_allocate() returns 0x00005555eba00000
2. Compiler expects int, reads only %eax: 0xeba00000
3. movslq %eax,%rbp sign-extends with bit 31 set
4. Result: 0xffffffffeba00000 (invalid pointer)
5. Dereferencing causes SEGFAULT

Files fixed:
1. hakmem_tiny_superslab_internal.h - Added box/ss_allocation_box.h
   (fixes superslab_head.c via transitive include)
2. hakmem_super_registry.c - Added box/ss_allocation_box.h

Warnings eliminated:
- "implicit declaration of function 'superslab_allocate'"
- "type of 'superslab_allocate' does not match original declaration"
- "code may be misoptimized unless '-fno-strict-aliasing' is used"

Test results:
- larson_hakmem now runs without segfault ✓
- Multiple test runs confirmed stable ✓
- 2 threads, 4 threads: All passing ✓

Impact:
- CRITICAL severity bug (affects all SuperSlab expansion)
- Intermittent (depends on memory layout ~50% probability)
- Now FIXED completely

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

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

core/hakmem_super_registry.c

@@ -1,5 +1,6 @@
 #include "hakmem_super_registry.h"
 #include "hakmem_tiny_superslab.h"
+#include "box/ss_allocation_box.h"  // For superslab_allocate() declaration
 #include <string.h>
 #include <stdio.h>
 #include <sys/mman.h>  // munmap for incompatible SuperSlab eviction

core/hakmem_tiny_superslab_internal.h

@@ -8,6 +8,7 @@
 
 #include "hakmem_tiny_superslab.h"
 #include "box/ss_hot_cold_box.h"
+#include "box/ss_allocation_box.h"  // CRITICAL: For superslab_allocate() declaration (fixes implicit int assumption)
 #include "hakmem_super_registry.h"
 #include "hakmem_tiny.h"
 #include "hakmem_tiny_config.h"

hakmem_super_registry.d

@@ -6,7 +6,8 @@ hakmem_super_registry.o: core/hakmem_super_registry.c \
  core/superslab/../hakmem_tiny_superslab_constants.h \
  core/superslab/../hakmem_tiny_config.h core/tiny_debug_ring.h \
  core/hakmem_build_flags.h core/tiny_remote.h \
- core/hakmem_tiny_superslab_constants.h
+ core/hakmem_tiny_superslab_constants.h core/box/ss_allocation_box.h \
+ core/hakmem_tiny_superslab.h
 core/hakmem_super_registry.h:
 core/hakmem_tiny_superslab.h:
 core/superslab/superslab_types.h:
@@ -20,3 +21,5 @@ core/tiny_debug_ring.h:
 core/hakmem_build_flags.h:
 core/tiny_remote.h:
 core/hakmem_tiny_superslab_constants.h:
+core/box/ss_allocation_box.h:
+core/hakmem_tiny_superslab.h: