fix(parser): dedupe HPE AHS DIMM inventory per slot, newest snapshot wins

The AHS blackbox stores a DIMM inventory snapshot per POST cycle and
parseDIMMs flattens all of them. dedupeMemory keyed on serial, so a slot
whose module was swapped between captures survived once per historical
occupant — a 24-slot board reported 26 modules and "same P/N" vs
"mixed P/N" configs looked identical.

dedupeMemory now collapses to one entry per non-empty slot with the last
(most recent, since token order follows chronological blackbox-record
order) occurrence winning. Slotless entries keep the serial/part fallback.

See ADL-060.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/parser/vendors/hpe_ilo_ahs/parser_test.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"git.mchus.pro/mchus/logpile/internal/models"
 	"git.mchus.pro/mchus/logpile/internal/parser"
 )
 
@@ -153,6 +154,34 @@ func TestParseAHSInventory(t *testing.T) {
 	}
 }
 
+func TestDedupeMemorySlotSwap(t *testing.T) {
+	// The AHS blackbox keeps one inventory snapshot per POST cycle. When a module
+	// is swapped between captures the same slot appears with different serials, in
+	// chronological (token stream) order. dedupeMemory must keep one entry per
+	// slot, with the most recent snapshot winning.
+	items := []models.MemoryDIMM{
+		{Slot: "PROC 1 DIMM 1", PartNumber: "HMCG94AHBRA480N", SerialNumber: "AAA1"},
+		{Slot: "PROC 1 DIMM 7", PartNumber: "HMCG94AHBRA487N", SerialNumber: "OLD7"},
+		{Slot: "PROC 1 DIMM 1", PartNumber: "HMCG94AHBRA480N", SerialNumber: "AAA1"}, // repeated snapshot
+		{Slot: "PROC 1 DIMM 7", PartNumber: "HMCG94AHBRA480N", SerialNumber: "NEW7"}, // module swapped
+	}
+
+	out := dedupeMemory(items)
+	if len(out) != 2 {
+		t.Fatalf("expected 2 DIMMs (one per slot), got %d: %+v", len(out), out)
+	}
+	bySlot := map[string]models.MemoryDIMM{}
+	for _, d := range out {
+		bySlot[d.Slot] = d
+	}
+	if got := bySlot["PROC 1 DIMM 7"].SerialNumber; got != "NEW7" {
+		t.Fatalf("expected newest occupant NEW7 for slot 7, got %q", got)
+	}
+	if got := bySlot["PROC 1 DIMM 1"].SerialNumber; got != "AAA1" {
+		t.Fatalf("unexpected serial for slot 1: %q", got)
+	}
+}
+
 func TestParseAHSTruncatedEntry(t *testing.T) {
 	p := &Parser{}
 	// Build archive where the last entry's declared size exceeds available data.