style: graph controls top-right, lift minimap, hide Save when unchanged

Controls -> top-right horizontal, no lock toggle; MiniMap !mb-10 so
it clears the activity bar; hide the per-script Save button when the
script is already at its latest save point (drafts still show Create).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/assets/AssetGraph/AssetGraphCanvas.svelte

@@ -598,11 +598,11 @@
 		--background-color={false}
 	>
 		<div class="absolute inset-0 !bg-surface-secondary h-full"></div>
-		<Controls />
+		<Controls position="top-right" orientation="horizontal" showLock={false} />
 		<MiniMap
 			pannable
 			zoomable
-			class="!bg-surface"
+			class="!bg-surface !mb-10"
 			nodeColor={(n) =>
 				n.type === 'asset'
 					? 'rgb(96 165 250 / 0.5)'

frontend/src/lib/components/assets/AssetGraph/AssetGraphDetailsPane.svelte

@@ -448,6 +448,23 @@
 		isDraft || (selection?.kind === 'runnable' && selection.runnable_kind === 'script')
 	)
 
+	// A persisted script with no edits vs its loaded version is already at
+	// its latest save point — hide Save for it. Drafts are never "saved"
+	// (always show Create). Unknown/loading → treat as dirty so Save isn't
+	// hidden when there might be changes.
+	let atLatestSavePoint = $derived.by(() => {
+		if (isDraft || !script) return false
+		const orig = scriptRes.current
+		if (!orig) return false
+		return (
+			script.content === orig.content &&
+			(script.tag ?? '') === (orig.tag ?? '') &&
+			(script.summary ?? '') === (orig.summary ?? '') &&
+			(script.description ?? '') === (orig.description ?? '') &&
+			JSON.stringify(script.schema ?? null) === JSON.stringify(orig.schema ?? null)
+		)
+	})
+
 	// Suffix editor for the draft-path popover. Seeded from the current
 	// path each time the popover opens so the user starts with what they
 	// see, not stale state from an earlier rename.
@@ -663,7 +680,7 @@
 					title="Open in full editor"
 				/>
 			{/if}
-			{#if isScriptView && script}
+			{#if isScriptView && script && !atLatestSavePoint}
 				<Button
 					variant="accent"
 					unifiedSize="sm"