Highlights
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1. Removed code duplication
• Introduced `extractItems` helper to safely unwrap API payloads.
• Simplified `getFormValues` to a single-line fallback expression.
• Replaced repeated list-extraction code in `loadModels`, `searchModels`,
and `refreshVendorCounts` with the new helper.
2. Vendor tab accuracy & performance
• Added `refreshVendorCounts` to recalc counts via a single lightweight
request; invoked only when必要 (current tab ≠ "all“) to avoid redundancy.
• `loadModels` still updates counts instantly when viewing "all", ensuring
accurate numbers on initial load and page changes.
3. Misc clean-ups
• Streamlined conditional URL building and state updates.
• Confirmed all async branches include error handling with i18n messages.
• Ran linter → zero issues.
Result: leaner, easier-to-maintain hook with correct, real-time vendor counts
and no repeated logic.
