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, 14 insertions, 0 deletions

diff --git a/src/features/surface-host/ui/SurfaceTable.svelte b/src/features/surface-host/ui/SurfaceTable.svelte
new file mode 100644
index 0000000..764cc36
--- /dev/null
+++ b/src/features/surface-host/ui/SurfaceTable.svelte
@@ -0,0 +1,14 @@
+<script lang="ts">
+	import Table from "../../../components/Table.svelte";
+	import { parseTablePayload } from "../logic/table";
+
+	let { payload }: { readonly payload: unknown } = $props();
+
+	// Parse defensively; an unparseable payload yields null → render nothing
+	// (graceful skip, per the custom-field contract).
+	const data = $derived(parseTablePayload(payload));
+</script>
+
+{#if data !== null}
+	<Table columns={data.columns} rows={data.rows} />
+{/if}