gitignore: ignore root RAM dumps (ROM stays tracked) and the Ghidra transient lock; untrack the lock file

.gitignore

@@ -52,3 +52,9 @@ harness/mame/cfg-net/
 # Test frame dumps written into the project root (the harness ignores them under harness/mame/)
 /*.ppm
 /*.pgm
+
+# RAM dumps written into the root (never the ROM: vt1200_v22.bin is tracked)
+/vt1200-ram-*.bin
+
+# Ghidra transient lock file (the project data directory is ignored separately)
+ghidra/vt1200.lock