docs: README cleanup for v0.2.0 multi-active model

- Rewrite §Scope from v0.1.0 to v0.2.0: lists multi-active +
  layout-slots as supported; restages deferred items per phase.
- Replace "active" with "open"/"focused" in API prose for
  unregister + update + render (no scalar `active` exists in
  v0.2.0).
- Add cross-ref under panel.open noting the v0.2.0 behavioral
  change (open does not auto-close other panels).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -31,23 +31,51 @@ graph LR
 ```
 <!-- topology:end -->
 
-## Scope (v0.1.0)
+## Scope (v0.2.0)
 
-v0.1 ships a minimal single-active-widget panel system:
+v0.2.0 ships multi-active panels with layout-slot positioning,
+preserving full backward-compatibility with v0.1.1's single-active
+callers via shim semantics. The lib is the generic UI-Framework
+substrate — domain-free per ADR-0001/ADR-0049, consumed by Display-
+Libs (inventory-list-display, crafting-display, notify-display) and
+modules (vagrant-skeleton).
 
-- Widget registry (register / unregister / open / close / toggle)
-- Theme system (13 configurable keys, capability-by-declaration guard)
-- Per-frame update with edge-detected mouse click + wheel dispatch
-- Context-menu (show, auto-reposition to screen bounds, hit-test, auto-close)
-- Default-trigger key binding via lib-core.input (lazy-required)
-- pause_on_open flag for game-pause gating
+### Supported (v0.2.0)
 
-**Intentional non-goals (deferred):**
-- Multi-widget z-order / stacking panels
-- Always-on HUD widgets (non-modal overlays)
-- Keyboard navigation within widgets
-- Panel animation (fade in / out)
-- Screen-size from engine (no Lua-accessible get_screen_size; v0.1 falls back to 1280x720 constants matching default Sporel window config)
+- Multi-active panels: multiple windows open simultaneously, each
+  rendered + hit-tested independently.
+- 11 layout-slot templates (center, left, right, top, bottom, four
+  corners, left-half, right-half) for common positioning.
+- Custom layout-fn hook `function(sw, sh) -> {x,y,w,h}` for bespoke
+  positioning (HUD elements, status displays, custom tool UIs).
+- Bw-Compat-Shim: v0.1.1 `register(id, widget)` ohne opts works
+  unchanged; `close()`/`is_open()` ohne arg map to focused = last-
+  opened.
+- Theme system: shared theme via `set_theme`/`get_theme` (unchanged).
+- Context-menu via `show_context_menu` (unchanged).
+- Default-trigger key-binding via `bind_default_trigger` (unchanged).
+
+### Deferred (v0.3.0+)
+
+- Z-order tiers (hud / normal / top) for layered rendering.
+- Persistent windows (always-open, exempt from ESC-close).
+- Input-block modes (none/self/all) for pass-through vs modal capture.
+- Map-editor-style multi-region UI as first-class persistent widgets.
+
+### Deferred (v0.4.0+)
+
+- Click-to-focus and explicit focus()/raise()/lower() API.
+- Drag-by-title-bar (draggable opt).
+- Resize-by-corner (resizable opt).
+- min/max-size constraints + screen-clamp.
+
+### Deferred (post-v0.4.0)
+
+- Window-decoration themes (per-window title-bar styles).
+- Touch/mobile input adaptation.
+- Window animations (slide-in, fade-in).
+- Window groups / tabbed-windows / MDI parent-child hierarchies.
+- Save/load of window-bounds across sessions.
 
 ## API
 
@@ -85,8 +113,9 @@ string. Loud-error on duplicate `widget_id` or missing required fields.
 
 **Syntax:** `panel.unregister(widget_id: string) -> void`
 
-Removes the widget from the registry. If the widget is currently active,
-closes the panel (sets active to nil, clears any open context-menu).
+Removes the widget from the registry. If the widget is currently open,
+closes it first (removes from open_order; clears any open context-menu
+if it was the last open window).
 
 ---
 
@@ -99,6 +128,10 @@ Opens `widget_id`. The window is pushed onto the top of `open_order`
 already open, it is brought to the front (re-focused). Loud-error if
 `widget_id` has not been registered.
 
+**v0.2.0 change:** `open(id)` no longer closes other open panels.
+Multiple panels can be visible simultaneously. See §Bw-Compat Guarantee
+below for the migration recipe.
+
 ---
 
 ### `panel.close(widget_id?)`
@@ -191,7 +224,7 @@ module-load-time cycles. Loud-error if `widget_id` is not registered.
 
 Must be called each game-update frame. Checks the default trigger key,
 reads mouse state, emits edge-detected click events (left and right
-independently), and dispatches wheel events. No-ops if no widget is active
+independently), and dispatches wheel events. No-ops if no panels are open
 (but still tracks mouse state to avoid spurious edges on next open).
 
 ---
@@ -202,7 +235,7 @@ independently), and dispatches wheel events. No-ops if no widget is active
 
 Must be called each render frame (inside the engine render phase). Draws
 the panel background, border, and title, then invokes `widget_def.render(ctx)`.
-If a context-menu is open, renders it on top. No-op if no widget is active.
+If a context-menu is open, renders it on top. No-op if no panels are open.
 
 ---
 
@@ -333,7 +366,7 @@ If you relied on the v0.1.1 "open(B) closes A" behavior, call
 
 ## Widget-Lifecycle-Contract
 
-Widget `render(ctx)` is called each render frame while the widget is active.
+Widget `render(ctx)` is called each render frame while the widget is open.
 Widget `handle_input(ctx, event)` is called for each dispatched input event.
 
 Both receive a `ctx` table:
@@ -347,7 +380,7 @@ ctx = {
         h = number,  -- content area height
     },
     theme      = table,   -- current merged theme (read-only by convention)
-    is_focused = bool,    -- true when this widget is the active one
+    is_focused = bool,    -- true when this widget is the focused one (last-opened)
 }
 ```