chore: merge Rust backend into monorepo

git-subtree-dir: server
git-subtree-mainline: fb6a84d75f
git-subtree-split: 8a88706ff9

server/.gitignore

@@ -0,0 +1,11 @@
+# Rust build output
+/target/
+/data/
+
+# Local configuration and secrets
+.env
+.env.*
+!.env.example
+
+# Graphify generated knowledge graphs
+/graphify-out/