Debug Counters Implementation - Clean History

Major Features:
- Debug counter infrastructure for Refill Stage tracking
- Free Pipeline counters (ss_local, ss_remote, tls_sll)
- Diagnostic counters for early return analysis
- Unified larson.sh benchmark runner with profiles
- Phase 6-3 regression analysis documentation

Bug Fixes:
- Fix SuperSlab disabled by default (HAKMEM_TINY_USE_SUPERSLAB)
- Fix profile variable naming consistency
- Add .gitignore patterns for large files

Performance:
- Phase 6-3: 4.79 M ops/s (has OOM risk)
- With SuperSlab: 3.13 M ops/s (+19% improvement)

This is a clean repository without large log files.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>

benchmarks/src/memset_test.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+int main() {
+    struct timespec t1, t2;
+    void* buf = malloc(2 * 1024 * 1024);
+    
+    clock_gettime(CLOCK_MONOTONIC, &t1);
+    memset(buf, 0xEF, 2 * 1024 * 1024);
+    clock_gettime(CLOCK_MONOTONIC, &t2);
+    
+    double ms = (t2.tv_sec - t1.tv_sec) * 1000.0 + (t2.tv_nsec - t1.tv_nsec) / 1000000.0;
+    
+    printf("memset time: %.3f ms\n", ms);
+    printf("First byte: 0x%02x (should be 0xEF)\n", ((unsigned char*)buf)[0]);
+    
+    free(buf);
+    return 0;
+}