feat: add 12 new vendor URL builders to Playwright image scraper
- Nokia, Huawei, Ciena, Moxa, D-Link, Alcatel-Lucent Enterprise,
Asterfusion, Brocade: passthrough builders (use stored product_page_url)
- NVIDIA Networking: SN-series URL builder (sn5600 → /ethernet-switching/sn5600/)
- Netgear: lowercase model slug builder for /business/wired/switches/fully-managed/
- UfiSpace: hardcoded sitemap-verified URL map (all 6 S9xxx models)
- QCT: hardcoded URL map for T3048-LY8 and T7032-IX1
- Add Nokia banner / Huawei marketing image patterns to GENERIC_IMAGE_PATTERNS
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