Add examples catalog with subcommand dispatch

- Extract game engine from package main to engine/ library package
- Create examples/ package with registry, Entry type, and BuilderDeps
- Register default world as an example (moved from main())
- Add combat example: two teams of units facing each other
- Rewrite main.go as thin dispatch: go run . example [name]
- Update README with examples catalog one-liner

1 files changed, 20 insertions, 0 deletions

diff --git a/engine/resource.go b/engine/resource.go
new file mode 100644
index 0000000..406750c
--- /dev/null
+++ b/engine/resource.go
@@ -0,0 +1,20 @@
+package engine
+
+import (
+	"time"
+
+	"age_of_empires/ecs"
+)
+
+type ResourceSource struct {
+	Remaining int
+}
+
+type ResourceGatherer struct {
+	MaxCapacity    int
+	CurrentVolume  int
+	Source         ecs.Entity
+	LastPickupTime time.Time
+}
+
+type ResourceStorage struct{}