Code Cleanup: Remove false positives, redundant validations, and reduce verbose logging

Following the C7 stride upgrade fix (commit 23c0d9541), this commit performs
comprehensive cleanup to improve code quality and reduce debug noise.

## Changes

### 1. Disable False Positive Checks (tiny_nextptr.h)
- **Disabled**: NXT_MISALIGN validation block with `#if 0`
- **Reason**: Produces false positives due to slab base offsets (2048, 65536)
  not being stride-aligned, causing all blocks to appear "misaligned"
- **TODO**: Reimplement to check stride DISTANCE between consecutive blocks
  instead of absolute alignment to stride boundaries

### 2. Remove Redundant Geometry Validations

**hakmem_tiny_refill_p0.inc.h (P0 batch refill)**
- Removed 25-line CARVE_GEOMETRY_FIX validation block
- Replaced with NOTE explaining redundancy
- **Reason**: Stride table is now correct in tiny_block_stride_for_class(),
  defense-in-depth validation adds overhead without benefit

**ss_legacy_backend_box.c (legacy backend)**
- Removed 18-line LEGACY_FIX_GEOMETRY validation block
- Replaced with NOTE explaining redundancy
- **Reason**: Shared_pool validates geometry at acquisition time

### 3. Reduce Verbose Logging

**hakmem_shared_pool.c (sp_fix_geometry_if_needed)**
- Made SP_FIX_GEOMETRY logging conditional on `!HAKMEM_BUILD_RELEASE`
- **Reason**: Geometry fixes are expected during stride upgrades,
  no need to log in release builds

### 4. Verification
- Build: ✅ Successful (LTO warnings expected)
- Test: ✅ 10K iterations (1.87M ops/s, no crashes)
- NXT_MISALIGN false positives: ✅ Eliminated

## Files Modified
- core/tiny_nextptr.h - Disabled false positive NXT_MISALIGN check
- core/hakmem_tiny_refill_p0.inc.h - Removed redundant CARVE validation
- core/box/ss_legacy_backend_box.c - Removed redundant LEGACY validation
- core/hakmem_shared_pool.c - Made SP_FIX_GEOMETRY logging debug-only

## Impact
- **Code clarity**: Removed 43 lines of redundant validation code
- **Debug noise**: Reduced false positive diagnostics
- **Performance**: Eliminated overhead from redundant geometry checks
- **Maintainability**: Single source of truth for geometry validation

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

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

core/tiny_nextptr.h

@@ -93,10 +93,15 @@ static inline __attribute__((always_inline)) void tiny_next_store(void* base, in
     }
 #endif
 
-    // Misalignment detector: class stride vs base offset
+    // DISABLED: Misalignment detector produces false positives
+    // Reason: Slab base offsets (2048, 65536) are not stride-aligned,
+    //         causing all blocks in a slab to appear "misaligned"
+    // TODO: Reimplement to check stride DISTANCE between consecutive blocks
+    //       instead of absolute alignment to stride boundaries
+#if 0
     do {
         static _Atomic uint32_t g_next_misalign_log = 0;
-        extern size_t tiny_block_stride_for_class(int class_idx);  // Includes header if enabled
+        extern size_t tiny_block_stride_for_class(int class_idx);
         size_t stride = (class_idx >= 0 && class_idx < 8) ? tiny_block_stride_for_class(class_idx) : 0;
         if (stride > 0) {
             uintptr_t delta = ((uintptr_t)base) % stride;
@@ -139,6 +144,7 @@ static inline __attribute__((always_inline)) void tiny_next_store(void* base, in
             }
         }
     } while (0);
+#endif
 
     if (off == 0) {
         // Aligned access at base.