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/hakmem_shared_pool.c

@@ -720,6 +720,7 @@ static inline void sp_fix_geometry_if_needed(SuperSlab* ss, int slab_idx, int cl
 
     // Reinitialize if capacity is off or class_idx mismatches.
     if (meta->class_idx != (uint8_t)class_idx || meta->capacity != expect_cap) {
+#if !HAKMEM_BUILD_RELEASE
         extern __thread int g_hakmem_lock_depth;
         g_hakmem_lock_depth++;
         fprintf(stderr, "[SP_FIX_GEOMETRY] ss=%p slab=%d cls=%d: old_cls=%u old_cap=%u -> new_cls=%d new_cap=%u (stride=%zu)\n",
@@ -727,6 +728,7 @@ static inline void sp_fix_geometry_if_needed(SuperSlab* ss, int slab_idx, int cl
                 meta->class_idx, meta->capacity,
                 class_idx, expect_cap, stride);
         g_hakmem_lock_depth--;
+#endif
 
         superslab_init_slab(ss, slab_idx, stride, 0 /*owner_tid*/);
         meta->class_idx = (uint8_t)class_idx;