feat(interests): desired-dimension form fields + size-desired column

Surfaces the recommender inputs added in Phase 2a (interests
.desired_length_ft / desired_width_ft / desired_draft_ft) on the
two interfaces reps actually use:

- /interests list: new "Berth size desired" column rendered as a
  compact "60×18×6 ft" string. Cells with no dimensions show "-";
  partial dimensions render "?" for the missing axis (recommender
  treats null as "no constraint").
- New/Edit Interest form: three optional length/width/draft inputs
  with explanatory subhead. Empty submissions collapse to undefined
  so the API doesn't see "" -> numeric coercion errors.
- createInterestSchema gains the three optional desired-dim fields
  with a shared transform that coerces strings/numbers to a positive
  2-decimal numeric string for the postgres `numeric` column.

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

src/lib/validators/interests.ts

@@ -10,6 +10,22 @@ import {
 
 // ─── Create ──────────────────────────────────────────────────────────────────
 
+/**
+ * Desired-dimension input. Strings/numbers are coerced to a positive
+ * decimal (string-typed for postgres `numeric` column compatibility);
+ * empty strings collapse to `undefined` so a blank form field doesn't
+ * round-trip "" → numeric error on the API.
+ */
+const optionalDesiredDimSchema = z
+  .union([z.string(), z.number()])
+  .optional()
+  .transform((v) => {
+    if (v === undefined || v === null || v === '') return undefined;
+    const n = typeof v === 'number' ? v : parseFloat(v);
+    if (!Number.isFinite(n) || n <= 0) return undefined;
+    return String(Math.round(n * 100) / 100);
+  });
+
 export const createInterestSchema = z.object({
   clientId: z.string().min(1),
   yachtId: z.string().optional(),
@@ -21,6 +37,9 @@ export const createInterestSchema = z.object({
   tagIds: z.array(z.string()).optional().default([]),
   reminderEnabled: z.boolean().optional().default(false),
   reminderDays: z.number().int().min(1).optional(),
+  desiredLengthFt: optionalDesiredDimSchema,
+  desiredWidthFt: optionalDesiredDimSchema,
+  desiredDraftFt: optionalDesiredDimSchema,
 });
 
 // ─── Update ──────────────────────────────────────────────────────────────────