feat: validate manifest version during pack command

Add validation to ensure the manifest_version matches the current expected
version (0.2) during the mcpb pack command. This prevents users from
packing extensions with outdated or incorrect manifest versions.

Changes:
- Add CURRENT_MANIFEST_VERSION constant to centralize version management
- Validate manifest version in pack command before creating bundle
- Update init command to use version constant
- Update tests to use version constant
- Fix prettier formatting issues

src/cli/pack.ts

@@ -13,7 +13,7 @@ import { basename, join, relative, resolve, sep } from "path";
 
 import { getAllFilesWithCount, readMcpbIgnorePatterns } from "../node/files.js";
 import { validateManifest } from "../node/validate.js";
-import { McpbManifestSchema } from "../schemas.js";
+import { CURRENT_MANIFEST_VERSION, McpbManifestSchema } from "../schemas.js";
 import { getLogger } from "../shared/log.js";
 import { initExtension } from "./init.js";
 
@@ -101,6 +101,17 @@ export async function packExtension({
     return false;
   }
 
+  const manifestVersion = manifest.manifest_version || manifest.dxt_version;
+  if (manifestVersion !== CURRENT_MANIFEST_VERSION) {
+    logger.error(
+      `ERROR: Manifest version mismatch. Expected "${CURRENT_MANIFEST_VERSION}", found "${manifestVersion}"`,
+    );
+    logger.error(
+      `  Please update the manifest_version in your manifest.json to "${CURRENT_MANIFEST_VERSION}"`,
+    );
+    return false;
+  }
+
   // Determine output path
   const extensionName = basename(resolvedPath);
   const finalOutputPath = outputPath