Install: Hekate 8GB after copy (fuse >4GiB), dram_fuse helper, RAM test target

- Add dram_fuse.c/h for shared fuse-to-MiB mapping
- After successful update/clean install copy: if hekate_8gb.bin exists and
  fuse reports more than 4 GiB, copy to sd:/payload.bin and
  sd:/bootloader/update.bin, then remove source; otherwise remove helper only
- Makefile: make ram-test builds output/RAM-Test.bin (tools/ram_test_main.c)

Made-with: Cursor

source/dram_fuse.c

@@ -0,0 +1,46 @@
+/*
+ * DRAM capacity from fuse (SKU), not physical probe.
+ */
+
+#include "dram_fuse.h"
+#include <soc/fuse.h>
+#include <soc/hw_init.h>
+#include <soc/t210.h>
+
+static int mariko_dram_mib(u32 dram_id)
+{
+	switch (dram_id) {
+	case 9:
+	case 13:
+	case 18:
+	case 21:
+	case 23:
+	case 28:
+		return 8192;
+	default:
+		if (dram_id >= 3 && dram_id <= 28)
+			return 4096;
+		return -1;
+	}
+}
+
+static int erista_dram_mib(u32 dram_id)
+{
+	if (dram_id == 4)
+		return 6144;
+	if (dram_id <= 6)
+		return 4096;
+	return -1;
+}
+
+int dram_capacity_mib_from_fuse(void)
+{
+	u32 nid = fuse_read_dramid(false);
+	u32 chip = hw_get_chip_id();
+
+	if (chip == GP_HIDREV_MAJOR_T210)
+		return erista_dram_mib(nid);
+	if (chip == GP_HIDREV_MAJOR_T210B01)
+		return mariko_dram_mib(nid);
+	return -1;
+}