mAi: #1 - schema: date_ranked_choice question type

New discriminated-union variant for `FeedbackQuestionSchema`:

  { type: 'date_ranked_choice',
    options: [{ id, start, end?, label? }, …],
    scale?: { min_label?, max_label? },
    allow_partial?: boolean }

- Times stored as UTC ISO 8601 strings (datetime with offset). Author UI
  feeds them through datetime-local inputs that the browser already treats
  as local time; renderer converts back to viewer-local on display.
- Rating scale is locked at 1-5 (5-point Likert) per design — the `scale`
  field exposes only labels, not min/max bounds.
- Per-option ids are 1-64 chars, alphanumeric + `-`/`_`, must be unique.
- 2-50 options per question.

Submission answer union extended with a `Record<string, 1|2|3|4|5|null>`
shape for the per-option rating map (`{ opt1: 5, opt2: null }`).

Refs m/fdbck#1.

src/lib/schemas.ts

@@ -10,6 +10,16 @@ const FeedbackQuestionBaseSchema = z.object({
 	help: z.string().max(500).optional(),
 });
 
+/** One date/time option in a `date_ranked_choice` question. Times are stored as UTC ISO 8601 strings. */
+export const DateRankedOptionSchema = z.object({
+	id: z.string().min(1).max(64).regex(/^[a-zA-Z0-9_-]+$/, {
+		message: 'option id may only contain letters, digits, "-" and "_"',
+	}),
+	start: z.string().datetime({ offset: true }),
+	end: z.string().datetime({ offset: true }).optional(),
+	label: z.string().max(200).optional(),
+});
+
 export const FeedbackQuestionSchema = z.discriminatedUnion('type', [
 	FeedbackQuestionBaseSchema.extend({
 		type: z.literal('short_text'),
@@ -37,6 +47,20 @@ export const FeedbackQuestionSchema = z.discriminatedUnion('type', [
 	FeedbackQuestionBaseSchema.extend({
 		type: z.literal('boolean'),
 	}),
+	FeedbackQuestionBaseSchema.extend({
+		type: z.literal('date_ranked_choice'),
+		options: z.array(DateRankedOptionSchema).min(2).max(50)
+			.refine(
+				(opts) => new Set(opts.map((o) => o.id)).size === opts.length,
+				{ message: 'date_ranked_choice option ids must be unique' },
+			),
+		// Scale is locked at 1-5 (5-point Likert) per design — only the labels are author-configurable.
+		scale: z.object({
+			min_label: z.string().max(50).optional(),
+			max_label: z.string().max(50).optional(),
+		}).optional(),
+		allow_partial: z.boolean().optional(),
+	}),
 ]);
 
 /** Version stamp like `0.260505` (YYMMDD) or `0.260505.b` for same-day re-edits. */
@@ -77,6 +101,14 @@ export const FeedbackInstanceUpdateSchema = z.object({
 
 const ANSWER_MAX = 5000;
 
+/** Per-option rating map for `date_ranked_choice` answers, e.g. `{ opt1: 5, opt2: null }`. */
+const DateRankedAnswerSchema = z.record(
+	z.string().min(1).max(64),
+	z.number().int().min(1).max(5).nullable(),
+).refine((m) => Object.keys(m).length <= 50, {
+	message: 'too many rated options',
+});
+
 export const FeedbackSubmissionSchema = z.object({
 	display_name: z.string().max(80).nullable().optional()
 		.transform((v) => (v && v.trim() ? v.trim().replace(/[\r\n]+/g, ' ') : null)),
@@ -88,6 +120,7 @@ export const FeedbackSubmissionSchema = z.object({
 			z.number(),
 			z.boolean(),
 			z.array(z.string().max(200)).max(20),
+			DateRankedAnswerSchema,
 			z.null(),
 		]),
 	),
@@ -121,3 +154,5 @@ export const ShareCreateSchema = z.object({
 
 export type FeedbackQuestion = z.infer<typeof FeedbackQuestionSchema>;
 export type FeedbackFormDefinition = z.infer<typeof FeedbackFormDefinitionSchema>;
+export type DateRankedOption = z.infer<typeof DateRankedOptionSchema>;
+export type DateRankedAnswer = z.infer<typeof DateRankedAnswerSchema>;