refactor(forms): replace custom querystring logic with Django {% querystring %} tag

[Deign86]

Replaces the manual querystring building in SearchForm.items(), urlencode(), and reset_offset() (and ChangesForm equivalents) with Django's built-in {% querystring %} template tag introduced in Django 5.1.

Changes

Python

• Removed SearchForm.items(), SearchForm.urlencode(), SearchForm.reset_offset() (weblate/trans/forms.py)
• Removed ChangesForm.items(), ChangesForm.urlencode() (weblate/trans/forms.py)
• Removed unused from django.utils.http import urlencode import
• Updated search() view in search.py to stop passing query_string/ search_url/ search_items to templates
• Updated ChangesView in changes.py: replaced self.changes_form.urlencode() with self.request.GET.urlencode()
• Updated edit.py views: removed search_url, search_items, reset_offset() references

Templates

• Updated paginator.html: pagination links now use {% querystring page=X limit=Y %}
• Updated change_list.html: all ?{{ query_string }} → ?{% querystring %}
• Updated translate.html, zen.html, zen-units.html: {{ search_url }} → {% querystring %}
• Updated embed-units.html, last-changes-content.html: same pattern

This simplifies the codebase by removing ~140 lines of manual querystring manipulation in favor of Django's built-in solution.

Closes #13638

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Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

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weblate/templates/paginator.html:45

• The paginator “jump to position” GET form no longer includes hidden inputs for the active filters/search parameters (previously provided via search_items). Submitting the position form will now drop all existing query params except page/limit, changing the result set unexpectedly. Preserve the current query parameters in the form submission (e.g., render hidden inputs from request.GET excluding page/limit, or use a querystring-based action that retains them).

      <a class="position-input-editable" title="{% translate "Go to position" %}">
        {# djlint:off #}
        {% if not paginator_form %}<form method="get"{% if anchor %} action="#{{ anchor }}"{% endif %}>{% endif %}
        {# djlint:on #}
        <input {% if paginator_form %}form="{{ paginator_form }}"{% endif %}
               type="hidden"
               name="limit"
               value="{{ page_obj.paginator.per_page }}"
               aria-label="{{ page_obj.paginator.per_page }}" />

weblate/templates/trans/change_list.html:51

• change_list.html now ends inside {% block content %} without closing {% if form.is_valid %}, without rendering the search <form method="get">…</form>, and without {% endblock content %}. This is a template syntax error and will break the changes page rendering. Restore the missing closing tags/content (or adjust the structure) so the template is complete.

{% block content %}
  {% if form.is_valid %}
    {% include "paginator.html" %}
    {% format_last_changes_content last_changes=object_list user=user %}