docs: add more-patterns OpenSpec change

Plan 6 additional built-in patterns mapped to digit keys 5-0.

openspec/changes/more-patterns/specs/pattern-placement/spec.md

@@ -0,0 +1,17 @@
+# Spec Delta
+
+## ADDED Requirements
+
+### Requirement: Additional built-in patterns are available
+The system SHALL provide additional built-in patterns (Beacon, Loaf, Boat, Tub, R-pentomino, Acorn) selectable via keys 5-0.
+
+#### Scenario: Select beacon
+- **WHEN** the user triggers `select:beacon`
+- **THEN** a beacon preview is shown
+
+### Requirement: New patterns support rotation
+The system SHALL support 90-degree rotation for all new patterns.
+
+#### Scenario: Rotate new pattern
+- **WHEN** the user rotates a new pattern preview
+- **THEN** its cells rotate accordingly