docs: align readme and docs with 0.5.0 (drop tailwind, add folder board)

Author: rb

README.md

@@ -5,7 +5,7 @@ NagVis, designed primarily for use **inside Checkmk**. Real-time live
 updates over Server-Sent Events, native Checkmk integration with
 main-menu entry and sidebar snapin, force-directed topology and geo
 boards. Built with **FastAPI** · **Vue 3** · **TypeScript** · **Vite** ·
-**Pinia** · **Tailwind CSS** · **D3.js**.
+**Pinia** · **D3.js**, on the Checkmk design system.
 
 > **Status:** early release. OrbVis is primarily designed as a Checkmk
 > integration and runs wherever Checkmk itself is supported. The
@@ -93,7 +93,7 @@ Frontend on `http://localhost:8741`, API docs on `http://localhost:8742/api/docs
 ```
 orbvis/
 ├── backend/          Python 3.12 + FastAPI (async), stdlib sqlite3
-├── frontend/         Vue 3 + TypeScript + Vite + Tailwind CSS
+├── frontend/         Vue 3 + TypeScript + Vite (Checkmk design system)
 ├── cmk_plugins/      Checkmk 2.4+ GUI plugins (sidebar, WATO permissions, menu)
 ├── cmk_plugins_23/   Checkmk 2.3 GUI plugins
 ├── scripts/          orbvis-setup / orbvis-install wrapper commands (in packages)

docs/architecture.md

@@ -8,7 +8,7 @@ the source of truth.
 ```
 ┌──────────────────────────────────────────────────────────────────┐
 │  Browser  ──────────────────────────────────────────────────────│
-│  Vue 3 SPA · TypeScript · Pinia · Vite · Tailwind · D3 v7        │
+│  Vue 3 SPA · TypeScript · Pinia · Vite · D3 v7                   │
 └────────────┬──────────────────────────────────────┬──────────────┘
              │ REST + JWT (access + refresh)        │ Server-Sent Events
              │ /api/v1/…                            │ /api/v1/sse/boards/{name}
@@ -46,6 +46,8 @@ Board types:
 - **Flow** — D3 force-directed topology
 - **Radar** — severity grid
 - **Geo** — Leaflet world map with lat/lng objects and polylines
+- **Folder** — Checkmk SETUP folder tree as a treemap with worst-state
+  bubbling; scales to six-digit host counts via SSE delta updates
 
 Object types are unified across board types (host, service, hostgroup,
 servicegroup, board link, line, textbox, image, graph, BI). The same

docs/comparison.md

@@ -49,6 +49,7 @@ Legend: ✅ done · 🟡 partial / different · ❌ not yet · ➕ new in OrbVis
 | Geo map (lat / lng) with Leaflet                | 🟡 [^2] | ✅     |
 | Force-directed topology (Flow board)            | ❌     | ➕     |
 | Severity grid (Radar board)                     | ❌     | ➕     |
+| Folder tree as treemap (Folder board)           | ❌     | ➕     |
 | Multi-select + bulk move                        | ❌     | ➕     |
 | Drag-drop reorder of boards on home screen      | ❌     | ➕     |
 | Inline edit panel (vs. modal-only edit)         | ❌     | ➕     |

docs/migration-from-nagvis.md

@@ -47,7 +47,7 @@ The `line_type` integer decomposes into three orthogonal OrbVis attributes:
 - **Backend connection definitions** — NagVis' `[backend_*]` sections are
   not converted. Configure backends in OrbVis via *Admin → Backends*
   (or `backends.json`).
-- **Custom CSS / templates** — OrbVis uses Vue + Tailwind, not PHP
+- **Custom CSS / templates** — OrbVis uses Vue components, not PHP
   templates. Visual customisation goes through board settings and the
   hover/context menu template fields.