benchmark/: three-way RE-tool comparison + first real C-lift

Three small functions extracted from the v1.19 conservative blob with
ground-truth C and per-tool (Ghidra / retdec / decomp.me) docs:
  01_memset        — byte memset, 28 B
  02_memcpy32      — word-aligned memcpy, 36 B
  03_magic_memset  — magic check + tail-call to memset, 40 B
  04_train_phy_block — first real poll-site function (104 B, 26 insts),
                       contains poll sites 12-15

Results in RESULTS.md:
  - Ghidra: A on all four. Auto-decompile is close to final.
  - retdec: A on #3, F on #1 and #2 (no register-arg inference on raw),
    C on #4 (mistakes & 0xF0000000 for < 0x10000000).

GRIND_LOG.md (in 04_train_phy_block/) records the matching-decomp
iteration: 116-byte candidate.c at -Os vs vendor 104 bytes = 89.7%
size match on first real iteration. Remaining gap is GCC's choice of
`cmp w, w_const; b.ls` over vendor's `tst w, #imm; b.eq` for the
mask tests.

gdb_debug/ holds a native-aarch64 GDB single-stepper for the three
benchmark functions — boltzmann smoke test passed (memset:
buf[10] 0x00→0xab).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

benchmark/02_memcpy32/retdec.c

@@ -0,0 +1,38 @@
+//
+// This file was generated by the Retargetable Decompiler
+// Website: https://retdec.com
+//
+
+#include <stdint.h>
+
+// ------------------- Function Prototypes --------------------
+
+int64_t entry_point(void);
+
+// ------------------------ Functions -------------------------
+
+// Address range: 0x1200 - 0x1224
+int64_t entry_point(void) {
+    // 0x1200
+    int64_t result; // 0x1200
+    int64_t v1 = result & 0xfffffffc; // 0x1200
+    if (v1 == 0) {
+        // 0x1210
+        return result;
+    }
+    int64_t v2 = 0;
+    int64_t v3 = v2 + 4; // 0x121c
+    while (v3 != v1) {
+        // 0x1214
+        v2 = v3;
+        v3 = v2 + 4;
+    }
+    // 0x1210
+    return result;
+}
+
+// --------------------- Meta-Information ---------------------
+
+// Detected compiler/packer: starforce (3.x)
+// Detected functions: 1
+