v1.0.0

Added

• Web Playground — Built-in browser UI served at GET / with ZPL/EPL editor, Labelary-style inch-based label size presets (4×6, 4×4, 4×3, 2×4, 2×2, 3.5×1.5, Custom), inline PNG preview, and one-click PNG/PDF download buttons
• Open File Support — Folder icon button in the playground opens a native file picker for .zpl/.epl files; format selector auto-detects from file extension
• labels_dir() / unit_dir() Test Helpers — Added render helper functions for consistent test data directory resolution across all test suites
• Release Version Skill — Reusable .github/skills/release-version/SKILL.md skill for cutting reproducible releases

Fixed

• debug_usps_text Path — Updated hardcoded test path after testdata reorganization

Changed

• Test Data Reorganization — Split ZPL test fixtures into testdata/labels/ (carrier/real-world) and testdata/unit/ (synthetic) subdirectories; flattened snippets into unit/; renamed _ref.png files to golden PNG convention
• Dual Diff Reports — Split the single diff report into two: testdata/diffs/diff_report_labels.txt and testdata/diffs/diff_report_unit.txt with separate canvas dimensions
• README Render Comparison — Updated section with current diff statistics and Labelary comparison gallery
• Documentation — Improved clarity of rendering instructions, test assertions, and AGENTS.md workflow documentation

Full Changelog: v0.5.0...v1.0.0