v1.0.1

## [1.0.0] - 2026-03-20

### Added

- Centered empty-state guidance in the blueprint viewport — first-time users now see welcome text, load/paste instructions, and keyboard shortcut hints instead of a blank canvas
- Grid-to-Blueprint export (`to_blueprint`) for full round-trip capability: blueprints can now be imported, modified, and exported back to a blueprint string
- `Display` implementation for the `Direction` enum, plus utility methods: `opposite()`, `rotate_cw()`, `rotate_ccw()`, and cardinal direction checks

### Changed

- Expanded `EntityCategory` coverage to classify all 78 registered prototype groups — chests, turrets, walls, gates, mining drills, solar panels, accumulators, roboports, labs, and train stops no longer render as grey `?`
- Unified duplicated entity classification logic into the `grid` crate, eliminating the divergence between `grid/render.rs` and `ui/colors.rs`

### Fixed

- Prototype lookup optimized from O(n) linear scan to O(1) `HashMap` via `OnceLock`, reducing per-entity overhead during blueprint import and grid placement

★ Insight ─────────────────────────────────────

• The to_blueprint addition is architecturally significant — it completes a round-trip data pipeline, which is a common milestone in format-handling tools. It's worth calling out explicitly in changelogs because it unlocks workflows that weren't previously possible.
• The OnceLock-based HashMap optimization is an implementation detail, but its user-facing effect (faster blueprint import/placement) is changelog-worthy — the entry frames it that way rather than mentioning OnceLock or std::sync.
• Expanding EntityCategory from 13 to ~15 groups is framed as a Fixed entry (grey ? was effectively a rendering bug) rather than Changed, since the prior behavior was unintentional rather than a deliberate design choice.
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