feat: add persistent dynamic panels

docs/UX_VERTICAL_SLICE.md

@@ -20,9 +20,12 @@ decision-shelf actions, usage-detail provenance, and end-to-end platform
 accessibility/IME.
 
 Panel lifecycle is now visible in the slice: every panel has a Detach action,
-the workspace bar has Add panel, and the sidebar exposes Detached sessions for
-reattachment. The wording is deliberate because panel removal keeps its session
-alive; termination is not exposed as a visually equivalent close action.
+the workspace bar opens an Add Panel chooser for Terminal, Browser, Markdown,
+and Review, and the sidebar and chooser expose Detached sessions for
+reattachment. Created panels are inserted beside the selection and receive a
+monotonic identity persisted with their ordering and attachment state in local
+SQLite. The wording is deliberate because panel removal keeps its session alive;
+termination is not exposed as a visually equivalent close action.
 
 Screenshots for the audit are stored outside Git under
 `~/shots/2026-08/lumbridge-ui-audit/`. Accessibility and IME correctness cannot
@@ -87,7 +90,7 @@ surface rather than a hosted Lumbridge control plane.
   leaving ordinary terminal arrows and text available to the PTY.
 - `Alt+1` through `Alt+6`: focus a pane directly while leaving terminal digits
   available to the PTY.
-- `Alt+Shift+N`: add or reattach the next panel in the deterministic slice.
+- `Alt+Shift+N`: open the Add Panel chooser; `1`–`4` create a typed panel.
 - `Alt+Shift+W`: detach the selected panel while its session keeps running.
 - `Cmd+K` on macOS or `Ctrl+K` on Linux: open the command palette.
 - `Shift+PageUp/PageDown`: move the selected live terminal through retained
@@ -98,8 +101,9 @@ surface rather than a hosted Lumbridge control plane.
   separate explicit action and is never triggered by focusing the pane.
 - `Escape` closes transient UI before it changes workspace state.
 
-Every command is represented by the shared interaction model so GPUI and Floem
-receive the same state transitions and tests.
+The six seed surfaces still replay through the shared interaction model so GPUI
+and Floem retain a comparable benchmark. Dynamic product panels use the GPUI
+panel registry until that contract moves into the framework-neutral UI crate.
 
 ## Decisive workload