fix(stock): repair Flexoptix stock write path

Two bugs blocked all Flexoptix stock_observations:
1. db.ts: compatible_brands null param needs ::text[] cast; price_currency needs
   ::bpchar cast in stock_observations INSERT
2. flexoptix-api-sync.ts: UPDATE transceivers used $1 in WHERE IS NOT NULL clause
   without explicit type cast — PostgreSQL cant infer type of untyped null params
   in WHERE context. Fixed with $1::text / $2::text casts.

Result: 346 stock observations written on first run after fix.

packages/scraper/src/robots/flexoptix-api-sync.ts

@@ -361,11 +361,11 @@ async function importProduct(
   if (product.imageUrl || product.url) {
     await pool.query(`
       UPDATE transceivers SET
-        image_url        = COALESCE(NULLIF(image_url, ''), $1),
-        product_page_url = COALESCE(NULLIF(product_page_url, ''), $2),
+        image_url        = COALESCE(NULLIF(image_url, ''), $1::text),
+        product_page_url = COALESCE(NULLIF(product_page_url, ''), $2::text),
         updated_at       = NOW()
       WHERE id = $3
-        AND ($1 IS NOT NULL OR $2 IS NOT NULL)
+        AND ($1::text IS NOT NULL OR $2::text IS NOT NULL)
     `, [product.imageUrl ?? null, product.url ?? null, transceiverId]);
   }
 

packages/scraper/src/utils/db.ts

@@ -461,8 +461,8 @@ export async function upsertStockObservation(params: {
        $5, $6::date,
        $7, $8::date,
        $9, $10::date,
-       $11, $12, $13, $14, $15,
-       $16, $17, $18, $19
+       $11, $12, $13::text[], $14, $15,
+       $16, $17::bpchar, $18, $19
      )`,
     [
       params.transceiverId,