refactor: remove vendored binaries and raw assets from repo

.gitignore

@@ -4,6 +4,11 @@ config.yaml
 # ISO output files
 *.iso
 
+# Vendored/runtime assets fetched outside git
+dcmtk-bin/
+legacy/raw/
+.local/
+
 # Temp directories
 /tmp/dicomdir_*
 
@@ -20,3 +25,10 @@ Thumbs.db
 
 # Local-only docs tell @VArtzy<farrelnikoson@gmail.com> for request
 docs/phases
+
+# Keep placeholder docs for ignored asset directories
+!dcmtk-bin/
+!dcmtk-bin/README.md
+!legacy/
+!legacy/raw/
+!legacy/raw/README.md