feat: Add support for per-project sandbox overlays (#294)

* feat: Add support for per-project sandbox overlays

* chore: Maintain consistency with TUI experience

* fix: Code review fixes

cmd/sandbox/project.go

@@ -0,0 +1,85 @@
+package sandbox
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/safedep/pmg/config"
+	"github.com/safedep/pmg/internal/ui"
+	pmgsandbox "github.com/safedep/pmg/sandbox"
+	"github.com/spf13/cobra"
+)
+
+// projectDeps is the dependency surface for `pmg sandbox project` subcommands.
+type projectDeps struct {
+	overlayDir func() string
+	repoRoot   func() (string, error)
+}
+
+func defaultProjectDeps() projectDeps {
+	return projectDeps{
+		overlayDir: func() string { return config.Get().SandboxOverlayDir() },
+		repoRoot:   resolveCurrentRepoRoot,
+	}
+}
+
+// resolveCurrentRepoRoot returns the git toplevel for the current working
+// directory, falling back to the cwd itself when not inside a git work tree.
+func resolveCurrentRepoRoot() (string, error) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	return pmgsandbox.ResolveRepoRoot(cwd)
+}
+
+// renderProjectSection prints the standard PMG section header
+// (blank line, cyan title, dashed separator).
+func renderProjectSection(out io.Writer, title string) error {
+	if _, err := fmt.Fprintln(out); err != nil {
+		return err
+	}
+	if _, err := fmt.Fprintln(out, ui.Colors.Cyan(title)); err != nil {
+		return err
+	}
+	_, err := fmt.Fprintln(out, ui.Colors.Normal("--------------------"))
+	return err
+}
+
+// renderKeyValueBlock prints aligned "Key: value" pairs with bold keys. Empty
+// values are skipped so optional fields do not produce empty lines.
+func renderKeyValueBlock(out io.Writer, entries [][2]string) error {
+	width := 0
+	for _, e := range entries {
+		if e[1] != "" && len(e[0]) > width {
+			width = len(e[0])
+		}
+	}
+	for _, e := range entries {
+		if e[1] == "" {
+			continue
+		}
+		label := fmt.Sprintf("%-*s", width+1, e[0]+":")
+		if _, err := fmt.Fprintf(out, "%s  %s\n", ui.Colors.Bold(label), e[1]); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// NewProjectCommand returns the `pmg sandbox project` parent command.
+func NewProjectCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "project",
+		Short: "Inspect and manage the current repository's sandbox overlay",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return cmd.Help()
+		},
+	}
+	deps := defaultProjectDeps()
+	cmd.AddCommand(newProjectShowCommand(deps))
+	cmd.AddCommand(newProjectResetCommand(deps))
+	cmd.AddCommand(newProjectListCommand(deps))
+	return cmd
+}