chore: housekeeping and refactoring (bump to 4.7.1)

- Remove unused parameters, dead files, and inaccurate doc.go files
- Extract shared helpers, eliminate duplication
- Rename cheatpath.Cheatpath to cheatpath.Path
- Optimize filesystem walks (WalkDir, skip .git)
- Move sheet name validation to sheet.Validate
- Move integration tests to test/integration/
- Consolidate internal/mock into mocks/
- Move fuzz.sh to test/
- Inline loadSheets helper into command callers
- Extract config.New into its own file
- Fix stale references in HACKING.md and CLAUDE.md
- Restore plan9 build target
- Remove redundant and low-value tests
- Clean up project documentation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/integration/brief_integration_test.go

@@ -0,0 +1,129 @@
+package integration
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+// TestBriefFlagIntegration exercises the -b/--brief flag end-to-end.
+func TestBriefFlagIntegration(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("integration test uses Unix-specific env vars")
+	}
+
+	// Build the cheat binary once for all sub-tests.
+	binPath := filepath.Join(t.TempDir(), "cheat_test")
+	build := exec.Command("go", "build", "-o", binPath, "./cmd/cheat")
+	build.Dir = repoRoot(t)
+	if output, err := build.CombinedOutput(); err != nil {
+		t.Fatalf("failed to build cheat: %v\nOutput: %s", err, output)
+	}
+
+	// Set up a temp environment with some cheatsheets.
+	root := t.TempDir()
+	sheetsDir := filepath.Join(root, "sheets")
+	os.MkdirAll(sheetsDir, 0755)
+
+	os.WriteFile(
+		filepath.Join(sheetsDir, "tar"),
+		[]byte("---\nsyntax: bash\ntags: [ compression ]\n---\ntar xf archive.tar\n"),
+		0644,
+	)
+	os.WriteFile(
+		filepath.Join(sheetsDir, "curl"),
+		[]byte("---\nsyntax: bash\ntags: [ networking, http ]\n---\ncurl https://example.com\n"),
+		0644,
+	)
+
+	confPath := filepath.Join(root, "conf.yml")
+	conf := fmt.Sprintf("---\neditor: vi\ncolorize: false\ncheatpaths:\n  - name: test\n    path: %s\n    readonly: true\n", sheetsDir)
+	os.WriteFile(confPath, []byte(conf), 0644)
+
+	env := []string{
+		"CHEAT_CONFIG_PATH=" + confPath,
+		"HOME=" + root,
+		"PATH=" + os.Getenv("PATH"),
+		"EDITOR=vi",
+	}
+
+	run := func(t *testing.T, args ...string) string {
+		t.Helper()
+		cmd := exec.Command(binPath, args...)
+		cmd.Dir = root
+		cmd.Env = env
+		output, err := cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("cheat %v failed: %v\nOutput: %s", args, err, output)
+		}
+		return string(output)
+	}
+
+	t.Run("brief output omits file path column", func(t *testing.T) {
+		output := run(t, "-b")
+		lines := strings.Split(strings.TrimSpace(output), "\n")
+
+		// Header should have title and tags but not file
+		if !strings.Contains(lines[0], "title:") {
+			t.Errorf("expected title: in header, got: %s", lines[0])
+		}
+		if !strings.Contains(lines[0], "tags:") {
+			t.Errorf("expected tags: in header, got: %s", lines[0])
+		}
+		if strings.Contains(lines[0], "file:") {
+			t.Errorf("brief output should not contain file: column, got: %s", lines[0])
+		}
+
+		// Data lines should not contain the sheets directory path
+		for _, line := range lines[1:] {
+			if strings.Contains(line, sheetsDir) {
+				t.Errorf("brief output should not contain file paths, got: %s", line)
+			}
+		}
+	})
+
+	t.Run("list output still includes file path column", func(t *testing.T) {
+		output := run(t, "-l")
+		lines := strings.Split(strings.TrimSpace(output), "\n")
+
+		if !strings.Contains(lines[0], "file:") {
+			t.Errorf("list output should contain file: column, got: %s", lines[0])
+		}
+	})
+
+	t.Run("brief with filter works", func(t *testing.T) {
+		output := run(t, "-b", "tar")
+		if !strings.Contains(output, "tar") {
+			t.Errorf("expected tar in output, got: %s", output)
+		}
+		if strings.Contains(output, "curl") {
+			t.Errorf("filter should exclude curl, got: %s", output)
+		}
+	})
+
+	t.Run("combined -lb works identically to -b", func(t *testing.T) {
+		briefOnly := run(t, "-b", "tar")
+		combined := run(t, "-lb", "tar")
+		if briefOnly != combined {
+			t.Errorf("-b and -lb should produce identical output\n-b:\n%s\n-lb:\n%s", briefOnly, combined)
+		}
+	})
+
+	t.Run("brief with tag filter works", func(t *testing.T) {
+		output := run(t, "-b", "-t", "networking")
+		if !strings.Contains(output, "curl") {
+			t.Errorf("expected curl in tag-filtered output, got: %s", output)
+		}
+		if strings.Contains(output, "tar") {
+			// tar is tagged "compression", not "networking"
+			t.Errorf("tag filter should exclude tar, got: %s", output)
+		}
+		if strings.Contains(output, "file:") {
+			t.Errorf("brief output should not contain file: column, got: %s", output)
+		}
+	})
+}