docs: use actual exported type names for tasks

`TaskConfig` is not exported anywhere; the generated TS type is
`TaskDefinition = Task | Command` with `Command = string | string[]`.

https://claude.ai/code/session_01N7sZTbj8K2QYvMAWUB1Nmz

Author: claude

docs/config/run.md

@@ -61,7 +61,7 @@ export default defineConfig({
 
 ## `run.tasks`
 
-- **Type:** `Record<string, TaskConfig | string | string[]>`
+- **Type:** `Record<string, TaskDefinition>` where `TaskDefinition = Task | string | string[]`
 
 Defines tasks that can be run with `vp run <task>`.