chore: bump version to 4.5.0

Bug fixes:
- Fix inverted pager detection logic (returned error instead of path)
- Fix repo.Clone ignoring destination directory parameter
- Fix sheet loading using append on pre-sized slices
- Clean up partial files on copy failure
- Trim whitespace from editor config

Security:
- Add path traversal protection for cheatsheet names

Performance:
- Move regex compilation outside search loop
- Replace string concatenation with strings.Join in search

Build:
- Remove go:generate; embed config and usage as string literals
- Parallelize release builds
- Add fuzz testing infrastructure

Testing:
- Improve test coverage from 38.9% to 50.2%
- Add fuzz tests for search, filter, tags, and validation

Documentation:
- Fix inaccurate code examples in HACKING.md
- Add missing --conf and --all options to man page
- Add ADRs for path traversal, env parsing, and search parallelization
- Update CONTRIBUTING.md to reflect project policy

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

internal/sheet/parse_extended_test.go

@@ -0,0 +1,54 @@
+package sheet
+
+import (
+	"runtime"
+	"testing"
+)
+
+// TestParseWindowsLineEndings tests parsing with Windows line endings
+func TestParseWindowsLineEndings(t *testing.T) {
+	// Only test Windows line endings on Windows
+	if runtime.GOOS != "windows" {
+		t.Skip("Skipping Windows line ending test on non-Windows platform")
+	}
+
+	// stub our cheatsheet content with Windows line endings
+	markdown := "---\r\nsyntax: go\r\ntags: [ test ]\r\n---\r\nTo foo the bar: baz"
+
+	// parse the frontmatter
+	fm, text, err := parse(markdown)
+
+	// assert expectations
+	if err != nil {
+		t.Errorf("failed to parse markdown: %v", err)
+	}
+
+	want := "To foo the bar: baz"
+	if text != want {
+		t.Errorf("failed to parse text: want: %s, got: %s", want, text)
+	}
+
+	want = "go"
+	if fm.Syntax != want {
+		t.Errorf("failed to parse syntax: want: %s, got: %s", want, fm.Syntax)
+	}
+}
+
+// TestParseInvalidYAML tests parsing with invalid YAML in frontmatter
+func TestParseInvalidYAML(t *testing.T) {
+	// stub our cheatsheet content with invalid YAML
+	markdown := `---
+syntax: go
+tags: [ test
+  unclosed bracket
+---
+To foo the bar: baz`
+
+	// parse the frontmatter
+	_, _, err := parse(markdown)
+
+	// assert that an error was returned for invalid YAML
+	if err == nil {
+		t.Error("expected error for invalid YAML, got nil")
+	}
+}