Initial Agentsd project commit

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/agentsd/src/paths.rs

@@ -0,0 +1,12 @@
+use std::path::PathBuf;
+
+/// Returns the `data/` directory next to the running executable.
+/// Creates it if it does not exist.
+pub fn data_dir() -> PathBuf {
+    let exe = std::env::current_exe().unwrap_or_else(|_| PathBuf::from("."));
+    let dir = exe.parent().unwrap_or_else(|| std::path::Path::new(".")).join("data");
+    if !dir.exists() {
+        std::fs::create_dir_all(&dir).ok();
+    }
+    dir
+}