Make action a thin wrapper around game-ci/unity-engine-core

Delegates build logic to the extracted implementation in
game-ci/unity-engine-core instead of maintaining a local copy, per
game-ci/roadmap#11 workstream 2 (Option A) — third and final engine
repo to make this move, after unity-activate and unity-test-runner.
src/model/* removed; build/test coverage (including the index.ts
orchestration integration tests) now lives in the destination repo.

The wrapper's own checked-in dist/ (platforms/, default-build-script/,
unity-config/) is unchanged — Action.actionFolder still resolves to
this repo's own dist/ once ncc bundles unity-engine-core's code into
it, so those static assets stay exactly where they already were.

yarn.lock

@@ -42,7 +42,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@actions/github@npm:^6.0.1":
+"@actions/github@npm:^6":
   version: 6.0.1
   resolution: "@actions/github@npm:6.0.1"
   dependencies:
@@ -753,6 +753,26 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@game-ci/unity-engine-core@game-ci/unity-engine-core#main":
+  version: 0.1.0
+  resolution: "@game-ci/unity-engine-core@https://github.com/game-ci/unity-engine-core.git#commit=e49341a2e524f830f2e2965fd84dd65f0ffce48c"
+  dependencies:
+    "@actions/cache": "npm:^4.1.0"
+    "@actions/core": "npm:^1.11.1"
+    "@actions/exec": "npm:^1.1.1"
+    "@actions/github": "npm:^6"
+    handlebars: "npm:^4.7.7"
+    md5: "npm:^2.3.0"
+    nanoid: "npm:^3.3.12"
+    semver: "npm:^7.7.4"
+    ts-md5: "npm:^1.3.1"
+    unity-changeset: "npm:^3.1.0"
+    xml-js: "npm:^1.6.11"
+    yaml: "npm:^2.8.4"
+  checksum: 10/477e9a01651fb0d3dbbfe99b1573ad70bec5b2151ab657cc8b720c34008ac78c276fed706628ccb5a3a5238bdf2418ac0afa46f18aa90cb7c37944c660cdb3be
+  languageName: node
+  linkType: hard
+
 "@graphql-typed-document-node/core@npm:^3.2.0":
   version: 3.2.0
   resolution: "@graphql-typed-document-node/core@npm:3.2.0"
@@ -3168,6 +3188,24 @@ __metadata:
   languageName: node
   linkType: hard
 
+"handlebars@npm:^4.7.7":
+  version: 4.7.9
+  resolution: "handlebars@npm:4.7.9"
+  dependencies:
+    minimist: "npm:^1.2.5"
+    neo-async: "npm:^2.6.2"
+    source-map: "npm:^0.6.1"
+    uglify-js: "npm:^3.1.4"
+    wordwrap: "npm:^1.0.0"
+  dependenciesMeta:
+    uglify-js:
+      optional: true
+  bin:
+    handlebars: bin/handlebars
+  checksum: 10/e755433d652e8a15fc02f83d7478e652359e7a4d354c4328818853ed4f8a39d4a09e1d22dad3c7213c5240864a65b3c840970b8b181745575dd957dd258f2b8d
+  languageName: node
+  linkType: hard
+
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   resolution: "has-flag@npm:4.0.0"
@@ -3759,6 +3797,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"minimist@npm:^1.2.5":
+  version: 1.2.8
+  resolution: "minimist@npm:1.2.8"
+  checksum: 10/908491b6cc15a6c440ba5b22780a0ba89b9810e1aea684e253e43c4e3b8d56ec1dcdd7ea96dde119c29df59c936cde16062159eae4225c691e19c70b432b6e6f
+  languageName: node
+  linkType: hard
+
 "minipass@npm:^7.0.4, minipass@npm:^7.1.2":
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   resolution: "minipass@npm:7.1.3"
@@ -3798,6 +3843,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"neo-async@npm:^2.6.2":
+  version: 2.6.2
+  resolution: "neo-async@npm:2.6.2"
+  checksum: 10/1a7948fea86f2b33ec766bc899c88796a51ba76a4afc9026764aedc6e7cde692a09067031e4a1bf6db4f978ccd99e7f5b6c03fe47ad9865c3d4f99050d67e002
+  languageName: node
+  linkType: hard
+
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   resolution: "nmtree@npm:1.0.6"
@@ -4411,6 +4463,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"sax@npm:^1.2.4":
+  version: 1.6.1
+  resolution: "sax@npm:1.6.1"
+  checksum: 10/bf7e7f8293903548bd663d71e9300b20ee04df178399b8f54029b6559225de422235c8fb0a63ba088fcb90c1dbaf9b475f57c7f32c901bfb78d0196dceb3cc7f
+  languageName: node
+  linkType: hard
+
 "semver@npm:^6.3.1":
   version: 6.3.1
   resolution: "semver@npm:6.3.1"
@@ -4500,6 +4559,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"source-map@npm:^0.6.1":
+  version: 0.6.1
+  resolution: "source-map@npm:0.6.1"
+  checksum: 10/59ef7462f1c29d502b3057e822cdbdae0b0e565302c4dd1a95e11e793d8d9d62006cdc10e0fd99163ca33ff2071360cf50ee13f90440806e7ed57d81cba2f7ff
+  languageName: node
+  linkType: hard
+
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   resolution: "stackback@npm:0.0.2"
@@ -4755,6 +4821,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"uglify-js@npm:^3.1.4":
+  version: 3.19.3
+  resolution: "uglify-js@npm:3.19.3"
+  bin:
+    uglifyjs: bin/uglifyjs
+  checksum: 10/6b9639c1985d24580b01bb0ab68e78de310d38eeba7db45bec7850ab4093d8ee464d80ccfaceda9c68d1c366efbee28573b52f95e69ac792354c145acd380b11
+  languageName: node
+  linkType: hard
+
 "undici-types@npm:~7.19.0":
   version: 7.19.2
   resolution: "undici-types@npm:7.19.2"
@@ -4782,10 +4857,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "unity-builder@workspace:."
   dependencies:
-    "@actions/cache": "npm:^4.1.0"
-    "@actions/core": "npm:^1.11.1"
-    "@actions/exec": "npm:^1.1.1"
-    "@actions/github": "npm:^6.0.1"
+    "@game-ci/unity-engine-core": "game-ci/unity-engine-core#main"
     "@types/node": "npm:^17.0.23"
     "@types/semver": "npm:^7.3.9"
     "@typescript/native-preview": "npm:^7.0.0-dev.20260505.1"
@@ -4797,19 +4869,13 @@ __metadata:
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     js-yaml: "npm:^4.1.0"
     lint-staged: "npm:^16.4.0"
-    md5: "npm:^2.3.0"
-    nanoid: "npm:^3.3.12"
     node-fetch: "npm:2"
     oxfmt: "npm:^0.48.0"
     oxlint: "npm:^1.63.0"
-    semver: "npm:^7.7.4"
-    ts-md5: "npm:^1.3.1"
     ts-node: "npm:10.8.1"
     typescript: "npm:4.7.4"
-    unity-changeset: "npm:^3.1.0"
     vite: "npm:^7"
     vitest: "npm:^4"
-    yaml: "npm:^2.8.4"
     yarn-audit-fix: "npm:^9.3.8"
   dependenciesMeta:
     lefthook:
@@ -5132,6 +5198,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"wordwrap@npm:^1.0.0":
+  version: 1.0.0
+  resolution: "wordwrap@npm:1.0.0"
+  checksum: 10/497d40beb2bdb08e6d38754faa17ce20b0bf1306327f80cb777927edb23f461ee1f6bc659b3c3c93f26b08e1cf4b46acc5bae8fda1f0be3b5ab9a1a0211034cd
+  languageName: node
+  linkType: hard
+
 "wrap-ansi@npm:^9.0.0":
   version: 9.0.2
   resolution: "wrap-ansi@npm:9.0.2"
@@ -5150,6 +5223,17 @@ __metadata:
   languageName: node
   linkType: hard
 
+"xml-js@npm:^1.6.11":
+  version: 1.6.11
+  resolution: "xml-js@npm:1.6.11"
+  dependencies:
+    sax: "npm:^1.2.4"
+  bin:
+    xml-js: ./bin/cli.js
+  checksum: 10/55ce342a47bf14a138a3fcea0c9e325b81484cfc1a8aac78df13b4d6ca01f20e32820572bc3e927cd9b61b9da9cdee4657cb2f304e460343d8d85d6a3659d749
+  languageName: node
+  linkType: hard
+
 "xml2js@npm:^0.5.0":
   version: 0.5.0
   resolution: "xml2js@npm:0.5.0"