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/doc.go

@@ -0,0 +1,65 @@
+// Package sheet provides functionality for parsing and managing individual cheat sheets.
+//
+// A sheet represents a single cheatsheet file containing helpful commands, notes,
+// or documentation. Sheets can include optional YAML frontmatter for metadata
+// such as tags and syntax highlighting preferences.
+//
+// # Sheet Format
+//
+// Sheets are plain text files that may begin with YAML frontmatter:
+//
+//	---
+//	syntax: bash
+//	tags: [networking, linux, ssh]
+//	---
+//	# Connect to remote server
+//	ssh user@hostname
+//
+//	# Copy files over SSH
+//	scp local_file user@hostname:/remote/path
+//
+// The frontmatter is optional. If omitted, the sheet will use default values.
+//
+// # Core Types
+//
+// The Sheet type contains:
+//   - Title: The sheet's name (derived from filename)
+//   - Path: Full filesystem path to the sheet
+//   - Text: The content of the sheet (without frontmatter)
+//   - Tags: Categories assigned to the sheet
+//   - Syntax: Language hint for syntax highlighting
+//   - ReadOnly: Whether the sheet can be modified
+//
+// Key Functions
+//
+//   - New: Creates a new Sheet from a file path
+//   - Parse: Extracts frontmatter and content from sheet text
+//   - Search: Searches sheet content using regular expressions
+//   - Colorize: Applies syntax highlighting to sheet content
+//
+// # Syntax Highlighting
+//
+// The package integrates with the Chroma library to provide syntax highlighting.
+// Supported languages include bash, python, go, javascript, and many others.
+// The syntax can be specified in the frontmatter or auto-detected.
+//
+// Example Usage
+//
+//	// Load a sheet from disk
+//	s, err := sheet.New("/path/to/sheet", []string{"personal"}, false)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//
+//	// Search for content
+//	matches, err := s.Search("ssh", false)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//
+//	// Apply syntax highlighting
+//	colorized, err := s.Colorize(config)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+package sheet