feat: add shared toolbox header and appearance

README.md

@@ -5,7 +5,7 @@ tools. An app always works by itself. When it receives a trusted same-origin
 catalog URL, the same app gains a toolbox home link and an app switcher without
 becoming coupled to a portal or client-side router.
 
-Version `0.1.0` contains three publish-ready packages:
+Version `0.2.0` contains three publish-ready packages:
 
 - `@add-ideas/toolbox-contract` — types, strict v1 runtime parsing, context
   discovery/loading, resolved URLs, and contextual link helpers.
@@ -160,23 +160,26 @@ import "@add-ideas/toolbox-shell-react/styles.css";
 <AppShell
   app={manifest}
   manifestUrl="/toolbox-app.json"
-  appActions={<a href="./help/">Help</a>}
+  helpAction={{ onClick: () => setHelpOpen(true) }}
   onContextError={(error) => console.warn(error)}
 >
   <Application />
 </AppShell>;
 ```
 
-The shell always renders app identity as an `h1`, version, derived privacy
-facts, manifest actions, and `appActions`. With valid context it additionally
-renders the catalog brand/home and a switcher at the accessible navigation
-landmark `Toolbox applications`. Destinations are ordinary links, so switching
-performs full-page navigation. On missing, cross-origin, invalid, or unavailable
-context the shell quietly remains usable in standalone mode; `onContextError` is
-optional observability.
+The shell always renders a centered app identity, version, derived privacy
+facts, standard Help and source controls, Personalize, Apps, manifest actions,
+and legacy `appActions`. With valid context it additionally renders the catalog
+brand/home and available app destinations. Destinations are ordinary links, so
+switching performs full-page navigation. On missing, cross-origin, invalid, or
+unavailable context the shell quietly remains usable in standalone mode;
+`onContextError` is optional observability.
 
 CSS custom properties prefixed with `--toolbox-` are the v1 theme surface. The
-catalog `light`, `dark`, or `system` mode selects the built-in palette.
+user's `light`, `dark`, or `system` preference is shared with same-origin apps
+under `TOOLBOX_PREFERENCES_KEY`; the catalog mode is used until a preference is
+saved. `ToolboxHeader` is also exported for portal-like pages that do not need
+the complete application shell.
 
 ## Validate a build
 
@@ -210,6 +213,8 @@ The main exports are:
   `fetchToolboxCatalog()`, `loadToolboxCatalog()`, and `loadToolboxContext()`.
 - URLs: `resolveWebUrl()`, `resolveToolboxApp()`, `requireSameOrigin()`, and
   `contextualizeToolboxLink()`.
+- Preferences: `parseToolboxPreferences()`, `readToolboxPreferences()`,
+  `writeToolboxPreferences()`, and `TOOLBOX_PREFERENCES_KEY`.
 
 See each emitted `.d.ts` file for the complete signatures.