feat(datatables): a shared data table is listed in the settings, read only

A fork could use its parent's data table but had nowhere to see that it
had one: the settings form reads the config, and the pointer lives outside
`datatables`. It is now a row of its own, naming the workspace it belongs
to, with no name to edit, no database to repoint and no delete — it is
configured, and its permissions administered, where it lives.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S5arH3G2Sa1Qqm32veJQ1n

backend/windmill-api/openapi.yaml

@@ -33920,6 +33920,19 @@ components:
                     type: object
                     description: Schema snapshot at fork time
                     additionalProperties: true
+        shared_datatables:
+          type: object
+          description: >-
+            Data tables of other workspaces that this one uses. Read-only here:
+            they are configured, and their permissions administered, in the
+            workspace named by `from`.
+          additionalProperties:
+            type: object
+            required: [from]
+            properties:
+              from:
+                type: string
+                description: The workspace this data table belongs to
     DatatableMigration:
       type: object
       required: [datatable, timestamp, name, code_up]

frontend/src/lib/components/workspaceSettings/DataTableSettings.svelte

@@ -13,12 +13,16 @@
 				resource_path?: string | undefined
 			}
 		}[]
+		/// Data tables of other workspaces that this one uses. Not this form's to
+		/// edit — they are configured, and their permissions administered, where
+		/// they live — so they are listed and left out of what it saves.
+		sharedDataTables: { name: string; from: string }[]
 	}
 
 	export function convertDataTableSettingsFromBackend(
 		settings: GetSettingsResponse['datatable']
 	): DataTableSettingsType {
-		const s: DataTableSettingsType = { dataTables: [] }
+		const s: DataTableSettingsType = { dataTables: [], sharedDataTables: [] }
 		if (settings?.datatables) {
 			for (const [name, rest] of Object.entries(settings.datatables)) {
 				s.dataTables.push({
@@ -28,6 +32,9 @@
 				})
 			}
 		}
+		for (const [name, entry] of Object.entries(settings?.shared_datatables ?? {})) {
+			s.sharedDataTables.push({ name, from: entry.from })
+		}
 		return s
 	}
 	export function convertDataTableSettingsToBackend(
@@ -316,7 +323,7 @@
 		</tr>
 	</Head>
 	<tbody class="divide-y bg-surface-tertiary">
-		{#if tempSettings.dataTables.length == 0}
+		{#if tempSettings.dataTables.length == 0 && tempSettings.sharedDataTables.length == 0}
 			<Row>
 				{#if wizardEnabled}
 					<Cell colspan={tableHeadNames.length} class="py-8">
@@ -492,6 +499,26 @@
 				</Cell>
 			</Row>
 		{/each}
+		{#each tempSettings.sharedDataTables as shared (shared.name)}
+			<Row>
+				<Cell first class="w-48">
+					<span class="text-sm">{shared.name}</span>
+				</Cell>
+				<Cell>
+					<span class="text-xs text-secondary">
+						Shared from <span class="font-medium">{shared.from}</span>
+					</span>
+					<Tooltip>
+						This data table belongs to {shared.from}. Everyone here reaches it with the roles
+						that workspace gives them, and it is configured there.
+					</Tooltip>
+				</Cell>
+				<Cell class="whitespace-nowrap">
+					<ExploreAssetButton asset={{ kind: 'datatable', path: shared.name }} />
+				</Cell>
+				<Cell class="w-12"></Cell>
+			</Row>
+		{/each}
 		{#if !wizardEnabled || tempSettings.dataTables.length > 0}
 			<Row class="!border-0">
 				<Cell colspan={tableHeadNames.length} class="pt-0 pb-2">

frontend/src/routes/(root)/(logged)/workspace_settings/+page.svelte

@@ -252,7 +252,7 @@
 		volumeStorage: undefined
 	})
 
-	let dataTableSettings: DataTableSettingsType = $state({ dataTables: [] })
+	let dataTableSettings: DataTableSettingsType = $state({ dataTables: [], sharedDataTables: [] })
 	let dataTableSettingsComponent: DataTableSettings | undefined = $state(undefined)
 
 	let dbtSettings: DbtSettingsType = $state({ warehouses: [] })