Decouple core Yaak logic from Tauri (#354)

crates/yaak-git/src/fetch.rs

@@ -0,0 +1,20 @@
+use crate::binary::new_binary_command;
+use crate::error::Error::GenericError;
+use crate::error::Result;
+use std::path::Path;
+
+pub fn git_fetch_all(dir: &Path) -> Result<()> {
+    let out = new_binary_command(dir)?
+        .args(["fetch", "--all", "--prune", "--tags"])
+        .output()
+        .map_err(|e| GenericError(format!("failed to run git pull: {e}")))?;
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let stderr = String::from_utf8_lossy(&out.stderr);
+    let combined = stdout + stderr;
+
+    if !out.status.success() {
+        return Err(GenericError(format!("Failed to fetch: {}", combined)));
+    }
+
+    Ok(())
+}