Sprint 1 complete: hybrid Compose + LibGDX architecture building

Full AL-001 through AL-008 implementation: shared/ module with ModuleType
enum, GameHost routing, StylusInputBridge, LineCorridorScreen with live
stroke rendering, LineScore (straightness + anglePrecision), score returned
to Compose hub via ActivityResult. Fixes LineScore field mismatch
(pressureConsistency → anglePrecision) caught during AL-009 build check.
Adds .gitignore and handoff notes.

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

.gitignore

@@ -0,0 +1,14 @@
+# Build outputs
+build/
+*/build/
+.gradle/
+
+# Local config
+local.properties
+
+# IDE
+.idea/
+*.iml
+
+# OS
+.DS_Store