1. Types

• [x] 1.1 Add WithOpenSpecOptions interface to src/types.ts (extends OpenSpecPluginOptions with nav?: boolean and sidebar?: boolean)
• [x] 1.2 Export WithOpenSpecOptions from src/index.ts

2. Implementation

• [x] 2.1 Implement withOpenSpec(config, options?) in src/plugin.ts
• [x] 2.2 Merge Vite plugin into config.vite.plugins (preserving existing plugins)
• [x] 2.3 Prepend nav entry to config.themeConfig.nav when nav !== false and themeConfig exists
• [x] 2.4 Inject sidebar section under /${outDir}/ key when sidebar !== false and sidebar is an object
• [x] 2.5 Export withOpenSpec from src/index.ts

3. Tests

• [x] 3.1 Test: withOpenSpec({}) calls generateOpenSpecPages and returns config with Vite plugin
• [x] 3.2 Test: nav entry is prepended when themeConfig.nav exists
• [x] 3.3 Test: sidebar section is injected under the correct key
• [x] 3.4 Test: nav: false skips nav injection
• [x] 3.5 Test: sidebar: false skips sidebar injection
• [x] 3.6 Test: existing Vite plugins are preserved

4. Documentation

• [x] 4.1 Update README to show withOpenSpec as the primary usage example
• [x] 4.2 Move existing verbose API to a "Advanced / manual setup" section
• [x] 4.3 Update JSDoc on withOpenSpec with example snippet showing other plugins alongside openspec
• [x] 4.4 Add usage note to README: "other Vite plugins go into vite.plugins as usual — withOpenSpec appends to the array without replacing it"