fix: widget edit crash (#185) + resizable textarea for complex fields

WidgetConfigDialog crashed on edit with React error #185 (Maximum update
depth exceeded) when the references/instances query returned undefined and
the inline '= []' fallback created a new array ref every render, looping the
auto-edit useEffect. Stabilize via useMemo(data ?? []). Also moved the
referencedWidgetIds Set inside the availableWidgets useMemo (clears the
pre-existing exhaustive-deps warning).

Complex config fields (promql, query, text, command, notes, or opt-in via
format: 'textarea') now render as a taller resizable Textarea (rows=6,
min-h-120px, font-mono, resize) in both WidgetConfigFields and
ServiceConfigFields, instead of a single-line Input.

Build + lint clean (referencedWidgetIds warning gone), 165 vitest pass.

frontend/src/pages/ServicesPage.tsx

@@ -5,6 +5,7 @@ import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
+import { Textarea } from "@/components/ui/textarea";
 import { Switch } from "@/components/ui/switch";
 import {
 	Dialog,
@@ -99,20 +100,33 @@ function ServiceConfigFields({
 	const properties =
 		(
 			type.config_schema as {
-				properties?: Record<string, { type?: string; description?: string }>;
+				properties?: Record<string, { type?: string; description?: string; format?: string }>;
 			}
 		).properties ?? {};
+	// Multi-line resizable textarea for fields that hold complex values (opt-in
+	// via `format: "textarea"`, or well-known multi-line keys).
+	const TEXTAREA_KEYS = new Set(["notes", "command"]);
 	return (
 		<div className="flex flex-col gap-3">
 			{Object.entries(properties).map(([key, schema]) => {
 				const isNumber = schema.type === "integer" || schema.type === "number";
+				const isTextarea = schema.format === "textarea" || TEXTAREA_KEYS.has(key);
 				return (
-					<Field
-						key={key}
-						label={key}
-						htmlFor={`cfg-${key}`}
-						helper={schema.description}
-					>
+				<Field
+					key={key}
+					label={key}
+					htmlFor={`cfg-${key}`}
+					helper={schema.description}
+				>
+					{isTextarea ? (
+						<Textarea
+							id={`cfg-${key}`}
+							rows={6}
+							className="resize font-mono text-xs min-h-[120px]"
+							value={String(config[key] ?? "")}
+							onChange={(e) => onChange({ ...config, [key]: e.target.value })}
+						/>
+					) : (
 						<Input
 							id={`cfg-${key}`}
 							type={isNumber ? "number" : "text"}
@@ -128,7 +142,8 @@ function ServiceConfigFields({
 								})
 							}
 						/>
-					</Field>
+					)}
+				</Field>
 				);
 			})}
 		</div>