feat(powershell): interactive db-query sample + docs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: claude

CHANGELOG.md

@@ -30,6 +30,12 @@ derived from git tags via [MinVer](https://github.com/adamralph/minver) (tag pre
   - **Templates** — reusable layouts are PowerShell functions returning parameterized subtrees;
     `samples/Strata.Demo.PowerShell` ships a `HostCard` template reused across `ping-monitor.ps1`
     and `uptime-monitor.ps1`.
+  - **Interactive Terminal.Gui apps** (`Strata.Dsl.TerminalGui` + `Show-StrataApp`) — full-screen
+    apps with focusable `Button` (`-OnSelect`), two-way-bound `TextField` (`-Bind`/`-OnChange`), and
+    scrollable/selectable `List` (`-Bind`/`-OnEnter`), driven by the reactive store. `StrataElement`
+    implements `IPseudoStateMutable` so the existing `FocusController`/`SelectionController` toggle
+    `:focused`/`:selected` on DSL elements. CSS `command:` keymaps register via
+    `Register-StrataCommand`. Sample: `samples/Strata.Demo.PowerShell/db-query.ps1`.
 - **Native widgets & overlay layout** — kind-aware projection of interactive controls and
   floating surfaces, in both renderers:
   - **Button** — a node of kind `Button` projects to a native control: a Terminal.Gui `Button`

samples/Strata.Demo.PowerShell/db-query.ps1

@@ -0,0 +1,38 @@
+#!/usr/bin/env pwsh
+# Interactive DB-query demo: type a query, press Run, scroll the results. Full-screen Terminal.Gui,
+# authored in PowerShell on the reactive store.
+#
+#   dotnet build src/Strata.Dsl.TerminalGui/Strata.Dsl.TerminalGui.csproj
+#   pwsh -File samples/Strata.Demo.PowerShell/db-query.ps1
+#
+# Tab/arrows move focus, Enter activates the focused control, Esc quits.
+
+$binDir = Resolve-Path "$PSScriptRoot/../../src/Strata.Dsl.TerminalGui/bin/Debug/net10.0"
+[System.Runtime.Loader.AssemblyLoadContext]::Default.add_Resolving({
+    param($context, $assemblyName)
+    $candidate = Join-Path $binDir "$($assemblyName.Name).dll"
+    if (Test-Path $candidate) { return $context.LoadFromAssemblyPath($candidate) }
+    return $null
+})
+Add-Type -Path (Join-Path $binDir 'Strata.Dsl.TerminalGui.dll')
+Import-Module "$PSScriptRoot/../../src/Strata.PowerShell/Strata.PowerShell.psd1" -Force
+
+# Stand-in data source so the demo runs with no database.
+function Invoke-DemoQuery([string]$q) {
+    1..8 | ForEach-Object { "row $_  ::  $q" }
+}
+
+$store = New-StrataStore @{ query = 'SELECT * FROM users'; rows = @() }
+
+$layout = Stack -Class 'app' {
+    Text 'DB Query' -Class 'h1'
+    TextField -Bind '$.query'
+    Button 'Run' -OnSelect {
+        param($ctx)
+        $q = $ctx.Store.State['query'].ToString()
+        Update-StrataStore $ctx.Store -Set '$.rows' -Value (Invoke-DemoQuery $q)
+    }
+    List -Bind '$.rows'
+}
+
+Show-StrataApp -Layout $layout -Store $store -Stylesheet "$PSScriptRoot/query.css"

samples/Strata.Demo.PowerShell/query.css

@@ -0,0 +1,8 @@
+/* Strata interactive demo — DB query tool. */
+Text.h1 { color: brightcyan; font-weight: bold; }
+TextField { color: brightwhite; }
+TextField:focused { color: black; background: brightcyan; }
+Button { color: brightgreen; }
+Button:focused { color: black; background: brightgreen; }
+List { color: white; }
+List:focused { color: brightyellow; }

src/Strata.PowerShell/README.md

@@ -48,6 +48,17 @@ while ($true) {
 }
 ```
 
+### Interactive apps (full-screen Terminal.Gui)
+- `Button 'Run' -OnSelect { param($ctx) ... }` — focusable button; handler gets `$ctx.Store/.Element/.Value`.
+- `TextField -Bind '$.query' -OnChange { ... }` — text input, two-way bound to store state.
+- `List -Bind '$.rows' -OnEnter { param($ctx) ... }` — scrollable, selectable list bound to an array.
+- `Register-StrataCommand -Name '<name>' -Action { param($ctx) ... }` — handler for a CSS
+  `command: "<name>" when "key.…"` keymap.
+- `Show-StrataApp -Layout $layout -Store $store -Stylesheet ./app.css` — blocks on the full-screen
+  Terminal.Gui loop (Tab/arrows move focus, Enter activates, Esc quits). Headless-safe.
+
+See `samples/Strata.Demo.PowerShell/db-query.ps1`.
+
 ### Templates
 A reusable layout is a function returning a parameterized subtree — see
 `samples/Strata.Demo.PowerShell/StrataTemplates.psm1` (`HostCard`), reused across the ping and