feat: track purchase site URL for new components

- New nullable purchase_url column on components
- Store/update validators accept an optional purchaseUrl (must be a valid
  absolute URL with a protocol when provided)
- components/create.vue: NewPartSearch import now also fills purchaseUrl
  from the scraped part's source URL (pc-builder.io product page); the
  field remains manually editable for second-hand parts entered by hand
- components/edit.vue: purchaseUrl is editable after creation
- components/show.vue: displays the purchase site as a clickable link
  when present
- 4 new functional tests: create with/without a purchase URL, invalid URL
  rejected (asserts the Inertia inputErrorsBag flash, not a raw 422 -
  content negotiation only returns JSON for XHR/API-style requests), and
  updating an existing component's purchase URL

app/validators/Components/store.ts

@@ -6,6 +6,13 @@ export const storeComponentValidator = vine.compile(
     price: vine.number().decimal([0, 2]).min(0),
     typeId: vine.number().min(1),
     purchaseDate: vine.string().regex(/^\d{4}-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])$/),
+    purchaseUrl: vine
+      .string()
+      .trim()
+      .url({ require_protocol: true })
+      .maxLength(2048)
+      .nullable()
+      .optional(),
     quantity: vine.number().min(1).withoutDecimals(),
   })
 )