Initial boilerplate scaffold for continuum-schemas

Protobuf data model (Template/PrintJob/MaterialProfile/PrintParameters)
with codegen targets for TypeBox+TS types (packages/ts-types) and
prost-derived Rust structs (packages/rust-types).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+node_modules/
+dist/
+target/
+*.log
+.env
+
+packages/ts-types/src/generated/*
+!packages/ts-types/src/generated/.gitkeep