Add G20 calibration assets, L20 compare, and refresh README.

Sync calibrated G20 URDF/MJCF/JSON lookup, L20 V10.1 dual-compare scripts,
joint GUI, and document O6/G20/L20 startup on the Gitea repo.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -25,3 +25,16 @@ dist/
 # Experiment outputs (regenerable)
 reports/
 tools/reports/
+
+# Runtime / local junk
+MUJOCO_LOG.TXT
+**/MUJOCO_LOG.TXT
+
+# Local backup / intermediate calibration dumps (keep named releases, drop *.bak*)
+*.bak
+*.bak_*
+**/*.bak
+**/*.bak_*
+**/*.urdf.bak*
+**/*.xml.bak*
+**/*.json.bak*