feat(show): add --id flag for IDs that look like flags

When an issue ID starts with dashes (e.g., gt--kzx), it can be
misinterpreted by Cobra's argument parser. The new --id flag allows
these IDs to be passed safely:

  bd show --id=gt--xyz

Multiple --id flags can be used, and they can be combined with
positional arguments.

Closes: bd-ix0ak

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/show_test.go

@@ -114,3 +114,83 @@ func TestShow_NoExternalRef(t *testing.T) {
 		t.Errorf("expected no 'External:' line for issue without external ref, got: %s", out)
 	}
 }
+
+func TestShow_IDFlag(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping CLI test in short mode")
+	}
+
+	// Build bd binary
+	tmpBin := filepath.Join(t.TempDir(), "bd")
+	buildCmd := exec.Command("go", "build", "-o", tmpBin, "./")
+	buildCmd.Dir = "."
+	if out, err := buildCmd.CombinedOutput(); err != nil {
+		t.Fatalf("failed to build bd: %v\n%s", err, out)
+	}
+
+	tmpDir := t.TempDir()
+
+	// Initialize beads
+	initCmd := exec.Command(tmpBin, "init", "--prefix", "test", "--quiet")
+	initCmd.Dir = tmpDir
+	if out, err := initCmd.CombinedOutput(); err != nil {
+		t.Fatalf("init failed: %v\n%s", err, out)
+	}
+
+	// Create an issue
+	createCmd := exec.Command(tmpBin, "--no-daemon", "create", "ID flag test", "-p", "1", "--json", "--repo", ".")
+	createCmd.Dir = tmpDir
+	createOut, err := createCmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("create failed: %v\n%s", err, createOut)
+	}
+
+	var issue map[string]interface{}
+	if err := json.Unmarshal(createOut, &issue); err != nil {
+		t.Fatalf("failed to parse create output: %v, output: %s", err, createOut)
+	}
+	id := issue["id"].(string)
+
+	// Test 1: Using --id flag works
+	showCmd := exec.Command(tmpBin, "--no-daemon", "show", "--id="+id, "--short")
+	showCmd.Dir = tmpDir
+	showOut, err := showCmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("show with --id flag failed: %v\n%s", err, showOut)
+	}
+	if !strings.Contains(string(showOut), id) {
+		t.Errorf("expected issue ID in output, got: %s", showOut)
+	}
+
+	// Test 2: Multiple --id flags work
+	showCmd2 := exec.Command(tmpBin, "--no-daemon", "show", "--id="+id, "--id="+id, "--short")
+	showCmd2.Dir = tmpDir
+	showOut2, err := showCmd2.CombinedOutput()
+	if err != nil {
+		t.Fatalf("show with multiple --id flags failed: %v\n%s", err, showOut2)
+	}
+	// Should see the ID twice (one for each --id flag)
+	if strings.Count(string(showOut2), id) != 2 {
+		t.Errorf("expected issue ID twice in output, got: %s", showOut2)
+	}
+
+	// Test 3: Combining positional and --id flag
+	showCmd3 := exec.Command(tmpBin, "--no-daemon", "show", id, "--id="+id, "--short")
+	showCmd3.Dir = tmpDir
+	showOut3, err := showCmd3.CombinedOutput()
+	if err != nil {
+		t.Fatalf("show with positional + --id failed: %v\n%s", err, showOut3)
+	}
+	// Should see the ID twice
+	if strings.Count(string(showOut3), id) != 2 {
+		t.Errorf("expected issue ID twice in output, got: %s", showOut3)
+	}
+
+	// Test 4: No args at all should fail
+	showCmd4 := exec.Command(tmpBin, "--no-daemon", "show")
+	showCmd4.Dir = tmpDir
+	_, err = showCmd4.CombinedOutput()
+	if err == nil {
+		t.Error("expected error when no ID provided, but command succeeded")
+	}
+}