Added:

- Full Git dependency support in `dcr.toml`
  - Support for `git`, `branch`, `tag`, and `rev` fields
  - Automatic cloning and checkout via `git2`
  - Dependencies are stored in `target/<profile>/deps/git/`
- New `dcr add` command for easy dependency management
  - Short syntax: `github:user/repo`, `gitlab:user/repo`, `path:/to/lib`
  - Automatic GitHub resolution for `git:user/repo`
- Visual feedback for dependency fetching with in-place status updates ("Fetching" → "Fetched")
- Modular dependency management architecture in `src/core/deps/`

src/core/deps/git.rs

@@ -0,0 +1,52 @@
+use std::path::Path;
+
+pub fn fetch_git_dep(
+    url: &str,
+    target_dir: &Path,
+    branch: Option<&str>,
+    tag: Option<&str>,
+    rev: Option<&str>,
+) -> Result<(), String> {
+    if target_dir.exists() {
+        return Ok(());
+    }
+
+    let mut builder = git2::build::RepoBuilder::new();
+    if let Some(b) = branch {
+        builder.branch(b);
+    }
+
+    let repo = builder
+        .clone(url, target_dir)
+        .map_err(|e| format!("failed to clone {}: {}", url, e))?;
+
+    if let Some(t) = tag {
+        checkout_ref(&repo, &format!("refs/tags/{}", t))?;
+    } else if let Some(r) = rev {
+        checkout_ref(&repo, r)?;
+    }
+
+    Ok(())
+}
+
+fn checkout_ref(repo: &git2::Repository, reference_str: &str) -> Result<(), String> {
+    let (object, reference) = repo
+        .revparse_ext(reference_str)
+        .map_err(|e| format!("failed to find ref {}: {}", reference_str, e))?;
+
+    repo.checkout_tree(&object, None).map_err(|e| {
+        let ref_name = reference.as_ref().and_then(|r| r.name()).unwrap_or("HEAD");
+        format!("failed to checkout {}: {}", ref_name, e)
+    })?;
+
+    match reference {
+        Some(gref) => {
+            let ref_name = gref.name().unwrap_or("HEAD");
+            repo.set_head(ref_name)
+        }
+        None => repo.set_head_detached(object.id()),
+    }
+    .map_err(|e| format!("failed to set HEAD: {}", e))?;
+
+    Ok(())
+}