feat(dashboard): Rhai source formatter with Format button

AST-based pretty-printer: tab-indented, 100-col print width, normalized
operator spacing, predictable reflow of long argument lists, comments
preserved verbatim. Refuses to emit on a parse failure and returns the
first error, so the Edit-tab button mirrors the JSON Format UX —
inline `.error.inline` banner; doc untouched on failure.

Patch bump to `0.5.1` across Cargo.toml workspace.package, the
dashboard package.json, and the docs/versioning.md Current versions
table.

Bundle delta versus the previous build: +6 KB raw, +1.5 KB gzipped.
Cumulative since the start of this work: +28 KB raw, +7.3 KB gzipped —
well under the +100 KB budget.

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

dashboard/src/routes/scripts/[id]/+page.svelte

@@ -14,6 +14,7 @@
 	import { logLevelColor, statusColor } from '$lib/styles';
 	import { guessHostKind, guessPathKind, pathKindMismatchWarning } from '$lib/route-utils';
 	import CodeEditor from '$lib/CodeEditor.svelte';
+	import { format as formatRhai } from '$lib/rhai';
 
 	/// Pretty-print a JSON string in place, leaving it untouched if the
 	/// input doesn't parse. The error state is shown next to the button
@@ -67,6 +68,17 @@
 	let editableSource = $state('');
 	let savingSource = $state(false);
 	let saveSourceError = $state<string | null>(null);
+	let rhaiFormatError = $state<string | null>(null);
+
+	function formatRhaiSource() {
+		const r = formatRhai(editableSource);
+		if (r.ok) {
+			editableSource = r.text;
+			rhaiFormatError = null;
+		} else {
+			rhaiFormatError = `Parse error at offset ${r.error.offset}: ${r.error.message}`;
+		}
+	}
 
 	async function saveSource() {
 		if (!script) return;
@@ -384,8 +396,16 @@
 		{#if tab === 'edit'}
 			<div class="grid">
 				<section class="card">
-					<h2>Source</h2>
+					<header class="editor-header">
+						<h2>Source</h2>
+						<button type="button" class="ghost small" onclick={formatRhaiSource}>
+							Format
+						</button>
+					</header>
 					<CodeEditor bind:value={editableSource} language="rhai" minHeight="22rem" />
+					{#if rhaiFormatError}
+						<div class="error inline">{rhaiFormatError}</div>
+					{/if}
 					{#if saveSourceError}
 						<div class="error inline">{saveSourceError}</div>
 					{/if}
@@ -794,6 +814,14 @@
 		font-size: 0.85rem;
 		color: #cbd5e1;
 	}
+	.editor-header {
+		display: flex;
+		justify-content: space-between;
+		align-items: center;
+	}
+	.editor-header h2 {
+		margin: 0;
+	}
 	button.link {
 		background: transparent;
 		color: #94a3b8;