[AlexAndBear]

Description

• Search bar: drops the page query when opening the search results, so a new term starts on page 1 instead of showing "No results found".
• ItemFilter / ItemFilterToggle: drop the page query when a filter changes, for the same reason.

Related Issue

• Fixes A new search or filter keeps the page number and shows "No results found" #3666

How Has This Been Tested?

• test environment: unit tests (Vitest)
• test case 1: navigating from the search bar to the results doesn't keep page
• test case 2: changing an ItemFilter selection removes page and keeps the other query params

Types of changes

• Bugfix
• Enhancement (a change that doesn't break existing code or deployments)
• Breaking change (a modification that affects current functionality)
• Technical debt (addressing code that needs refactoring or improvements)
• Tests (adding or improving tests)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)