Escape strings in projector configuration files

Embedding tags containing quotes, backslashes or newlines produce invalid or altered projector_config.pbtxt strings. Paths are also interpolated directly into protobuf text.

Reproduced on Linux / Python 3.12 against upstream commit 48a5f8aee532e086bebacfd0613260874e8899f9. A deterministic regression and focused fix are prepared.

This report was prepared with AI assistance.