docs(protocol): plugin-spec package.json example prints the scaffolder's TypeScript floor (#17376)

The `package.json` distribution-format example in
`content/docs/protocol/kernel/plugin-spec.mdx` declared a `typescript` floor of
`^5.0.0`, which admits 5.0-5.2 — versions two other doc pages already state are
not supported. Updated it to the value the scaffolders currently emit
(`^5.3.0`, `SCAFFOLD_TYPESCRIPT_RANGE` in `packages/cli/src/commands/init.ts`)
and added an adjacent sentence naming that constant as the authority, so the
snippet stops being a second value someone has to remember to keep in sync.


Claude-Session: https://claude.ai/code/session_012GKcPZbMoGq7WPzKLfRBTU

Co-authored-by: Claude <noreply@anthropic.com>

Author: baozhoutao

content/docs/protocol/kernel/plugin-spec.mdx

@@ -705,7 +705,7 @@ Plugins are distributed as **NPM packages** for easy versioning and distribution
 
   "devDependencies": {
     "@objectstack/cli": "^2.0.0",
-    "typescript": "^5.0.0"
+    "typescript": "^5.3.0"
   },
 
   "keywords": [
@@ -721,6 +721,10 @@ Plugins are distributed as **NPM packages** for easy versioning and distribution
 }
 ```
 
+The `typescript` floor above mirrors `SCAFFOLD_TYPESCRIPT_RANGE` in
+`packages/cli/src/commands/init.ts` — that constant, not this snippet, is the
+authority the scaffolders emit from.
+
 ### Publishing to NPM
 
 ```bash