Review must-fix: LICENSE, dangling ref, obsolete markers

- LICENSE (MIT, own work) + README license section
- FINDINGS.md per-version notes point into docs/firmware/
- checksum brute-forcers marked superseded (code + tool docs)

tools/lofi_checksum_crack.py

@@ -1,5 +1,8 @@
 #!/usr/bin/env python3
-"""Long-running checksum cracker for Lofi-12 XT cmtd+0x08.
+"""SUPERSEDED 2026-09-30: checksum solved (see lofi_image.compute_checksum).
+Kept for methodology only — do not run expecting new results.
+
+Long-running checksum cracker for Lofi-12 XT cmtd+0x08.
 
 Strategy: 3 known (image, checksum) pairs let us test each hypothesis fast
 with early exit, plus detect CONSTANT-XOR-masked CRCs (stored = crc ^ mask).