codec-re: add segment 1 block dumper for analysis

Investigated multi-segment Tran continuation but couldn't crack it.
Each hypothesis tried (segment header consumes 0/1/2 T deltas, blocks
continue Tran with various interpretations) breaks at sample ~512.

Block budget for V70 segment 1: 264 nibbles + 244 RLE zeros = 508
deltas — exactly the segment size. So the block structure CAN encode
508 single-channel samples, but applying segment 1 blocks as Tran
gives wrong values.

Most likely the channel ordering changes in segment 1+ (e.g., segment
0 = Tran, segment 1 = Vert, segment 2 = Long, etc.) but I couldn't
verify cleanly.  Stopping here — segment-0 Tran decode is solid and
multi-segment work needs more fresh thinking.

analysis/seg1_blocks.py

@@ -0,0 +1,28 @@
+"""Dump all blocks in segment 1 of each event with their data."""
+import sys
+sys.path.insert(0, ".")
+from minimateplus.waveform_codec import walk_body, find_data_start
+
+
+def main():
+    for stem in ("M529LL1A.SP0", "M529LL1L.JQ0", "M529LL1L.V70"):
+        path = f"decode-re/5-11-26/{stem}"
+        with open(path, "rb") as f:
+            body = f.read()[43:-26]
+        blocks = walk_body(body, find_data_start(body))
+
+        # Find segment 1 (between first and second 40 02)
+        seg40_indices = [i for i, b in enumerate(blocks) if b.tag_hi == 0x40]
+        if len(seg40_indices) < 2:
+            print(f"\n{stem}: only {len(seg40_indices)} segment headers found")
+            seg1_blocks = blocks[seg40_indices[0]:] if seg40_indices else []
+        else:
+            seg1_blocks = blocks[seg40_indices[0]:seg40_indices[1]+1]
+        print(f"\n=== {stem} segment 1 ({len(seg1_blocks)} blocks) ===")
+        for b in seg1_blocks[:25]:
+            tag = f"{b.tag_hi:02x}{b.tag_lo:02x}"
+            print(f"  off={b.offset:>5} {tag} NN=0x{b.tag_lo:02x}({b.tag_lo:>3}) len={b.length:>3}  data={b.data[:16].hex(' ')}{'...' if len(b.data)>16 else ''}")
+
+
+if __name__ == "__main__":
+    main()