Phase 83-1 + Allocator Comparison: Switch dispatch fixed (NO-GO +0.32%), PROFILE correction, SCORECARD update

Key changes:
- Phase 83-1: Switch dispatch fixed mode (tiny_inline_slots_switch_dispatch_fixed_box) - NO-GO (marginal +0.32%, branch reduction negligible)
  Reason: lazy-init pattern already optimal, Phase 78-1 pattern shows diminishing returns

- Allocator comparison baseline update (10-run SSOT, WS=400, ITERS=20M):
  tcmalloc: 115.26M (92.33% of mimalloc)
  jemalloc: 97.39M (77.96% of mimalloc)
  system: 85.20M (68.24% of mimalloc)
  mimalloc: 124.82M (baseline)

- hakmem PROFILE correction: scripts/run_mixed_10_cleanenv.sh + run_allocator_quick_matrix.sh
  PROFILE explicitly set to MIXED_TINYV3_C7_SAFE for hakmem measurements
  Result: baseline stabilized to 55.53M (44.46% of mimalloc)
  Previous unstable measurement (35.57M) was due to profile leak

- Documentation:
  * PERFORMANCE_TARGETS_SCORECARD.md: Reference allocators + M1/M2 milestone status
  * PHASE83_1_SWITCH_DISPATCH_FIXED_RESULTS.md: Phase 83-1 analysis (NO-GO)
  * ALLOCATOR_COMPARISON_QUICK_RUNBOOK.md: Quick comparison procedure
  * ALLOCATOR_COMPARISON_SSOT.md: Detailed SSOT methodology

- M2 milestone status: 44.46% (target 55%, gap -10.54pp) - structural improvements needed

🤖 Generated with Claude Code
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

core/front/tiny_c3_inline_slots.h

@@ -0,0 +1,73 @@
+// tiny_c3_inline_slots.h - Phase 77-1: C3 Inline Slots Fast-Path API
+//
+// Goal: Zero-overhead always-inline push/pop for C3 FIFO ring buffer
+// Scope: C3 allocations (64-128B)
+// Design: Fail-fast to unified_cache on full/empty
+//
+// Fast-Path Strategy:
+//   - Always-inline push/pop for zero-call-overhead
+//   - Modulo arithmetic inlined (tail/head)
+//   - Return NULL on empty, 0 on full (caller handles fallback)
+//   - No bounds checking (ring size fixed at compile time)
+//
+// Integration Points:
+//   - Alloc: Call c3_inline_pop() in tiny_front_hot_box BEFORE unified_cache
+//   - Free: Call c3_inline_push() in tiny_legacy_fallback BEFORE unified_cache
+//
+// Rationale:
+//   - Same pattern as C4/C5/C6 inline slots (proven +7.05% cumulative)
+//   - Conservative cap (256) = 2KB/thread (Phase 77-0 recommendation)
+//   - Fail-fast design = no performance cliff if full/empty
+
+#ifndef HAK_FRONT_TINY_C3_INLINE_SLOTS_H
+#define HAK_FRONT_TINY_C3_INLINE_SLOTS_H
+
+#include <stdint.h>
+#include "../box/tiny_c3_inline_slots_tls_box.h"
+#include "../box/tiny_c3_inline_slots_env_box.h"
+#include "../box/tiny_inline_slots_fixed_mode_box.h"
+
+// ============================================================================
+// C3 Inline Slots: Fast-Path Push/Pop (Always-Inline)
+// ============================================================================
+
+// Get TLS pointer for C3 inline slots
+// Inline for zero overhead
+static inline TinyC3InlineSlots* c3_inline_tls(void) {
+    extern __thread TinyC3InlineSlots g_tiny_c3_inline_slots;
+    return &g_tiny_c3_inline_slots;
+}
+
+// Push pointer to C3 inline ring
+// Returns: 1 if success, 0 if full (caller must fallback to unified_cache)
+__attribute__((always_inline))
+static inline int c3_inline_push(TinyC3InlineSlots* slots, void* ptr) {
+    // Check if ring is full
+    if (__builtin_expect(c3_inline_full(slots), 0)) {
+        return 0;  // Full, caller must use unified_cache
+    }
+
+    // Enqueue at tail
+    slots->slots[slots->tail] = ptr;
+    slots->tail = (slots->tail + 1) % TINY_C3_INLINE_CAPACITY;
+
+    return 1;  // Success
+}
+
+// Pop pointer from C3 inline ring
+// Returns: non-NULL if success, NULL if empty (caller must fallback to unified_cache)
+__attribute__((always_inline))
+static inline void* c3_inline_pop(TinyC3InlineSlots* slots) {
+    // Check if ring is empty
+    if (__builtin_expect(c3_inline_empty(slots), 0)) {
+        return NULL;  // Empty, caller must use unified_cache
+    }
+
+    // Dequeue from head
+    void* ptr = slots->slots[slots->head];
+    slots->head = (slots->head + 1) % TINY_C3_INLINE_CAPACITY;
+
+    return ptr;  // Success
+}
+
+#endif // HAK_FRONT_TINY_C3_INLINE_SLOTS_H