fix: merge GridStackView into DashboardView (#19)

DashboardView and GridStackView rendered the same three charts from the
same hardcoded data, so every chart factory method existed twice. The
dashboard is now the GridStackLayout variant at @Route(""):

- GridStackView deleted, its grid/toolbar/chart factories moved into
  DashboardView, which keeps the point-click notifications the old
  dashboard had.
- Charts size to their widget (100%/100%) instead of a fixed 400px.
- MainLayout has one dashboard entry; nav.gridstack/page.gridstack keys
  dropped from all three bundles.
- Storage key is "dashboard" (was "gridstack-demo"), so a saved layout
  from the old route is not reused.
- GridStackViewTest renamed to DashboardViewTest, plus a test asserting
  the three charts render.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0124BiJikbhbiEsNfJxdWM69

CLAUDE.md

@@ -39,7 +39,7 @@ Since `apex-chart.ts` renders into light DOM (`createRenderRoot()` returns `this
 
 **`GridStackLayout`/`GridStackItem`** (`components/`) wrap [gridstack.js](https://gridstack.js.org) 13.1.0 for draggable/resizable grids. Unlike `ApexChart`, the bridge (`frontend/components/grid-stack.ts`) is a plain `HTMLElement`, not a Lit component — its children are server-rendered `GridStackItem`s living in light DOM, and a Lit render root would fight gridstack for ownership of them. A `MutationObserver` calls `makeWidget`/`removeWidget` as Flow adds/removes children, so there's no explicit add/remove protocol to the client. Every `GridStackItem` needs a stable `gs-id` (auto-generated if not given) — `GridStackLayout.setStorageKey(...)` persists drag/resize state to browser `localStorage` keyed on it and restores by matching ids, so items lose their saved position if their id changes between reloads. Item styling (`.grid-stack-item-content`) extends the `--dialect-*` alias layer in `styles.css`, same as `.dialect-card`.
 
-**Views** (`views/`): `MainLayout` (`@Layout`, applies to all routes) is the `AppLayout` shell — navbar + `SideNav` drawer, with one `SideNavItem` per route. Routes: `DashboardView` (`@Route("")`) wraps each chart in a `Card` (`components/Card.java`); `FormView` (`@Route("formular")`) demonstrates form controls bound via `Binder`; `TableView` (`@Route("tabelle")`) demonstrates a `Grid` over dummy data with a live text filter (`GridListDataView.addFilter`, `TextField` in `ValueChangeMode.EAGER`). New views should reuse `Card` to wrap their content rather than adding components directly, and get a matching `SideNavItem` in `MainLayout`.
+**Views** (`views/`): `MainLayout` (`@Layout`, applies to all routes) is the `AppLayout` shell — navbar + `SideNav` drawer, with one `SideNavItem` per route. Routes: `DashboardView` (`@Route("")`) puts each chart in a `Card` (`components/Card.java`) inside a `GridStackItem` of a `GridStackLayout`, so widgets are draggable/resizable and the layout is persisted to `localStorage`; charts use `width: 100%` / `height: 100%` to fill their widget rather than a fixed pixel height; `FormView` (`@Route("formular")`) demonstrates form controls bound via `Binder`; `TableView` (`@Route("tabelle")`) demonstrates a `Grid` over dummy data with a live text filter (`GridListDataView.addFilter`, `TextField` in `ValueChangeMode.EAGER`). New views should reuse `Card` to wrap their content rather than adding components directly, and get a matching `SideNavItem` in `MainLayout`.
 
 **Styling**: `src/main/resources/META-INF/resources/styles.css` is the one project-level stylesheet (loaded via `@StyleSheet("styles.css")` in `Application.java`). It defines `--dialect-*` design tokens (Dialect design system: primary orange `#E86C00`, cool-gray background, card radius/shadow) and aliases them onto Aura's own CSS custom properties (`--aura-accent-color-*`, `--aura-background-color-*`, `--aura-orange`, `--aura-yellow`) rather than fighting the theme. Aura tokens use OKLCH + relative-color syntax and accept plain hex overrides. When restyling, prefer extending this alias layer over hardcoding new colors in components.