feat: v0.4 components, loaders, command palette rework, overlay a11y fixes

[Shewart]

Summary

The first 0.4 feature batch: 14 new components, a rebuilt Loading with 23 variants, a reworked command palette, and fixes found while testing the demo against what the CLI installs. Merge after v0.3.0 is tagged; Directory.Build.props is untouched, so it merges cleanly onto main.

New components (90 direct targets, up from 76; 194 registry entries)

Each is written once in ShellUI.Components and its CLI template generated from that file. TemplateSyncTests keeps the two copies identical. Sub-parts are hidden (IsAvailable = false) and install automatically with their parent.

Target	What it is	Installs with it
kbd	Keyboard key hint
aspect-ratio	Fixed-ratio container
button-group	Joined buttons, horizontal or vertical
toggle-group	Single- or multi-select toggles (@bind-Value / @bind-Values)	toggle-group-item
input-group	Input with Prefix / Suffix slots
number-input	−/+ input with min, max and step
stat-card	KPI tile with trend badge
timeline	Continuous line with a dot on each event	timeline-item
tree-view	Expandable, selectable tree (@bind-SelectedValue)	tree-view-item
qr-code	QR code as SVG	NuGet QRCoder 1.8.0
image-viewer	Thumbnail with a zoomable lightbox (Escape and backdrop close)
chat	AI chat panel pinned to the newest message	chat-message, chat-input
chat-message	Bubble with streaming indicator; Text keeps line breaks
chat-input	Enter sends, Shift+Enter adds a line

None of them use custom JavaScript.

Loading: rebuilt, 23 variants

• Self-contained: keyframes are prefixed shellui-loading-* and ship inside the component. Before, the bars animations only existed in init's CSS, so they never animated for NuGet users.
• Smoother: animates only transform and opacity.
• Recolourable: uses currentColor, so Class="text-…" changes it.
• Accessible: role="status", and it slows down under reduced motion rather than stopping.
• Culture-safe: fixes delays that were invalid CSS in decimal-comma locales.
• New variants: logo (the ShellUI mark, sweeping between logo and its inverse; theme-aware), snake, rows, columns, sequence, twinkle, activity, chase, dual-ring, wave, typing, ripple, progress, shimmer.
• Redrawn: orbit, as an SVG with a comet tail.

Command palette

• Command rewritten: anchored near the top of the screen, filters as you type, ↑/↓/Home/End/Enter, the highlighted row scrolls into view and follows the mouse, optional Group headings, a footer with key hints and a count, and a "No results" state. No custom JavaScript.
• CommandItem moved to a hidden command-models template. This fixes the rc.2 compile error, where the class sat after @code and was never compiled.
• CommandPalette gains bindable IsOpen / IsOpenChanged, so a button and Ctrl+K can share the same state.

Fixes

• shellui.js shortcuts required Ctrl and ⌘, so Ctrl+K never fired. Either key now works (package and CLI copies).
• Dialog, AlertDialog, Sheet and Drawer: focus moves in on open, Escape closes, and they have role="dialog" and aria-modal.
• alert-dialog didn't compile: it was missing its Variants import.
• shellui add now adds @using ….Components.UI.Variants / .Components.Models to _Imports.razor once files in those namespaces exist.
• init writes h1:focus { outline: none; }, restoring the stock rule that FocusOnNavigate relies on (lost when init overwrites app.css).
• Radar chart tooltips were pinned to the top of the chart and now follow the pointer (FollowCursor).
• TreeView hover looked identical to selected; hover now uses bg-muted and rows no longer touch.

Demo

• New pages: a "New in 0.4" section on the home page and at /components/new.
• Loaders grid: shows all 23 variants.
• Brought up to date through the CLI: SidebarProvider, shellui.js and the chart files (which added wwwroot/css/charts.css) were stale and are now reinstalled. This fixes Ctrl+B.
• Ctrl+K: the header uses CommandPalette. A leftover layout Ctrl+K handler that closed the palette 33 ms after opening is removed.
• EmptyState: "Upload File" now opens a file picker.
• app.css: rebuilt in Release, so it's minified.

Docs

• Roadmap: the 0.4 components are added and the ShellDocs items marked done; the composable Select/ContextMenu/NavigationMenu/Carousel parts are listed as package-only.
• Counts and dependencies: registry counts are updated across the docs, and the dependency table has the new entries.

Tests (129 passing, up from 107)

• Sync: template/package sync for all new components and command.
• Shortcuts: accept Ctrl or ⌘.
• _Imports wiring: RequiredImports adds the right namespaces.
• init CSS: keeps the h1:focus rule.
• Existing sweeps now cover the new components: syntax, dependency graph, Class parameter, no external icon fonts.

Test plan

• Clean Release build of ShellUI.slnx: 0 warnings, 0 errors
• dotnet test: 129/129
• Fresh dotnet new blazor + init + add with all 90 components: builds with 0 warnings, _Imports updated automatically
• Parent-only install (toggle-group timeline tree-view chat command qr-code) pulls in all hidden sub-parts and QRCoder
• Demo checked in the browser: new components, toggle and tree state, chat with real Enter/Shift+Enter keypresses, image viewer, Escape on all dialog types, Ctrl+K (real keypress) and Ctrl+B on the dashboard layout, loader geometry, logo loader in light and dark themes, radar tooltip placement
• CI

Follow-ups

• Reconcile the three drifted copies of each component (package, CLI templates, demo), then generate templates from the package at build time.
• Popover and Dropdown: Escape handling, and click-outside for Dropdown.
• feat/init-dashboard: wire dashboard layouts on init / add.