feat(views,surface-host): Extensions sidebar view — auto-expanded surfaces + tables

views (new feature):
- pure panel-stack reducer + thin generic ViewSidebar (dropdown picker + add/remove),
  switches on view KIND, never a surface id

Extensions view (composition root):
- folds frontend modules + backend surfaces into one "Extensions" view
- frontend module list AGGREGATED from each feature's public `manifest` export
  (can't drift); no per-module version (FE features are internal to dispatch-web)
- surfaces are AUTO-SUBSCRIBED on catalog + rendered expanded (no catalog buttons)

surface-host:
- consecutive `stat` fields coalesce into one aligned label/value table (StatTable)
- generic custom-field renderer: dispatch on rendererId === "table" → SurfaceTable
  (pure parseTablePayload), so a backend `custom`/table field renders generically
- shared presentational components/Table.svelte (used by both, neither feature
  depends on the other)

store:
- auto-subscribe every catalog entry, unsubscribe vanished ones, re-subscribe all
  on reconnect; expose all received specs via `surfaces` (drops single-selection)

backend-handoff: CR-1 — emit Loaded Extensions as a custom/table field; notes
what's already covered FE-side (renderer shipped, stat-table fallback works).

1 files changed, 21 insertions, 0 deletions

diff --git a/src/features/surface-host/ui/StatTable.svelte b/src/features/surface-host/ui/StatTable.svelte
new file mode 100644
index 0000000..415423f
--- /dev/null
+++ b/src/features/surface-host/ui/StatTable.svelte
@@ -0,0 +1,21 @@
+<script lang="ts">
+	import type { StatFieldView } from "../logic/types";
+
+	// Renders a run of stat fields as one aligned label/value table. Headerless:
+	// the column semantics aren't known generically, but the two-column layout
+	// gives the tidy, aligned readout the stats deserve (e.g. extension → version).
+	let { stats }: { readonly stats: readonly StatFieldView[] } = $props();
+</script>
+
+<div class="overflow-x-auto">
+	<table class="table table-sm">
+		<tbody>
+			{#each stats as stat, i (i)}
+				<tr>
+					<th class="font-medium">{stat.label}</th>
+					<td class="text-right tabular-nums">{stat.value}</td>
+				</tr>
+			{/each}
+		</tbody>
+	</table>
+</div>