Fix extension materialization to move bundles into container (#2339)

* Migrate extension plugin materialization layout

Materialize extension plugins into a dedicated extensions/ container, validate the new manifest convention, and bump extension plugin versions.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Keep extension manifests source-compatible

Restore source extension manifests to "extensions": "." while preserving materialization-time rewrite to "extensions" in distribution output.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Validate canvas extension layout for external submissions

Add intake and quality-gate checks for canvas-tagged external plugins so they must include extensions/extension.mjs and optional manifest extensions is validated when present.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Fix plugin clean extension pass and typo guard text

Declare EXTENSIONS_DIR in clean-materialized-plugins and run extension cleanup once after plugin cleanup. Also normalize misspelled-key detection strings to satisfy spelling checks without changing validation behavior.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Proper codespell fix

* Separate canvas structure quality gate status

Track canvas structure as its own gate status and output, include it in aggregate summaries, and enforce Git object types so extensions/ is a tree and extensions/extension.mjs is a blob.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Move extension bundles during materialization

Change extension-plugin materialization to move root bundle entries into extensions/ instead of copying them, and assert originals are removed in test coverage.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Nest materialized extension bundles by plugin name

Materialize extension plugins into extensions/<plugin-name>/... (moved entries) so resulting paths are duplicated by design, and bump extension plugin versions to the next patch release.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Fix extension materialization publish and cleanup

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

* Preserve root extension logo asset

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: d26008fb-9928-4ba7-b7c8-36f35320f7c1

eng/materialize-plugins.test.mjs

@@ -4,6 +4,7 @@ import os from "os";
 import path from "path";
 import { after, test } from "node:test";
 import { materializeExtensionPlugin } from "./materialize-plugins.mjs";
+import { cleanMaterializedExtensionPlugin } from "./clean-materialized-plugins.mjs";
 
 const tempDirs = [];
 
@@ -13,7 +14,7 @@ after(() => {
   }
 });
 
-test("materializeExtensionPlugin writes extension bundles to ./extensions and rewrites manifest", () => {
+test("materializeExtensionPlugin writes extension bundles to ./extensions and preserves root logo assets", () => {
   const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "materialize-extension-plugin-"));
   tempDirs.push(tempDir);
 
@@ -32,17 +33,57 @@ test("materializeExtensionPlugin writes extension bundles to ./extensions and re
   fs.writeFileSync(path.join(pluginDir, "assets", "preview.png"), "fake-image-bytes");
 
   const result = materializeExtensionPlugin(pluginDir);
+  const bundleRoot = path.join(pluginDir, "extensions", "extension-plugin");
 
   assert.equal(result.skipped, false);
   assert.equal(result.manifestUpdated, true);
-  assert.equal(result.copiedEntries, 3);
-  assert.equal(fs.existsSync(path.join(pluginDir, "extensions", "extension.mjs")), true);
-  assert.equal(fs.existsSync(path.join(pluginDir, "extensions", "assets", "preview.png")), true);
-  assert.equal(fs.existsSync(path.join(pluginDir, "extensions", "README.md")), true);
+  assert.equal(result.movedEntries, 3);
+  assert.equal(fs.existsSync(path.join(bundleRoot, "extension.mjs")), true);
+  assert.equal(fs.existsSync(path.join(bundleRoot, "assets", "preview.png")), true);
+  assert.equal(fs.existsSync(path.join(bundleRoot, "README.md")), true);
   assert.equal(fs.existsSync(path.join(pluginDir, "extensions", ".github")), false);
+  assert.equal(fs.existsSync(path.join(pluginDir, "extension.mjs")), false);
+  assert.equal(fs.existsSync(path.join(pluginDir, "README.md")), false);
+  assert.equal(fs.existsSync(path.join(pluginDir, "assets", "preview.png")), true);
 
   const pluginManifest = JSON.parse(
     fs.readFileSync(path.join(pluginDir, ".github", "plugin", "plugin.json"), "utf8")
   );
   assert.equal(pluginManifest.extensions, "extensions");
+  assert.equal(pluginManifest.logo, "assets/preview.png");
+});
+
+test("cleanMaterializedExtensionPlugin restores moved extension files to root", () => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "clean-materialized-extension-plugin-"));
+  tempDirs.push(tempDir);
+
+  const pluginDir = path.join(tempDir, "extension-plugin");
+  fs.mkdirSync(path.join(pluginDir, ".github", "plugin"), { recursive: true });
+  fs.mkdirSync(path.join(pluginDir, "assets"), { recursive: true });
+  fs.writeFileSync(path.join(pluginDir, ".github", "plugin", "plugin.json"), JSON.stringify({
+    name: "test-extension-plugin",
+    description: "test plugin",
+    version: "1.0.0",
+    logo: "assets/preview.png",
+    extensions: ".",
+  }, null, 2));
+  fs.writeFileSync(path.join(pluginDir, "extension.mjs"), "export default {};\n");
+  fs.writeFileSync(path.join(pluginDir, "README.md"), "# test\n");
+  fs.writeFileSync(path.join(pluginDir, "assets", "preview.png"), "fake-image-bytes");
+
+  materializeExtensionPlugin(pluginDir);
+  const result = cleanMaterializedExtensionPlugin(pluginDir);
+
+  assert.equal(result.removed, 3);
+  assert.equal(result.manifestUpdated, true);
+  assert.equal(fs.existsSync(path.join(pluginDir, "extension.mjs")), true);
+  assert.equal(fs.existsSync(path.join(pluginDir, "README.md")), true);
+  assert.equal(fs.existsSync(path.join(pluginDir, "assets", "preview.png")), true);
+  assert.equal(fs.existsSync(path.join(pluginDir, "extensions")), false);
+
+  const pluginManifest = JSON.parse(
+    fs.readFileSync(path.join(pluginDir, ".github", "plugin", "plugin.json"), "utf8")
+  );
+  assert.equal(pluginManifest.extensions, ".");
+  assert.equal(pluginManifest.logo, "assets/preview.png");
 });