feat: CI orchestrator — Lambda dispatch + Fargate routing + cancel

dispatch: receives Gitea webhook, routes by runs-on label to Fargate
  tasks (go/node/docker/godot) or Lambda executor (deploy).
  Path filter evaluation, DynamoDB run tracking, cancel via StopTask.
exec: lightweight Lambda for deploy-only jobs (S3 sync, ECS update).
SAM template: API Gateway + 2 Lambdas + DynamoDB + cleanup cron.

orchestrator/test-event.json

@@ -0,0 +1,9 @@
+{
+  "body": "{\"ref\":\"refs/heads/main\",\"before\":\"0000000\",\"after\":\"abc1234567890\",\"repository\":{\"id\":1,\"name\":\"studio\",\"full_name\":\"tinqs/studio\",\"clone_url\":\"https://tinqs.com/tinqs/studio.git\",\"html_url\":\"https://tinqs.com/tinqs/studio\"},\"pusher\":{\"login\":\"ozan\",\"email\":\"ozan@tinqs.com\"},\"commits\":[{\"id\":\"abc1234567890\",\"message\":\"test push\",\"added\":[\"cmd/tstudio/main.go\"],\"removed\":[],\"modified\":[]}]}",
+  "headers": {
+    "x-gitea-event": "push",
+    "content-type": "application/json"
+  },
+  "httpMethod": "POST",
+  "path": "/webhook"
+}