Improve property limit widgets with enum detection and value extraction
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p><strong>Depends on:</strong> [project/ai!1545] which adds <code>PropertyLimitWidgetHelper</code>.</p>
<ul>
<li>The Tools Explorer rendered a plain <code><textarea></code> for every property's "Values" field, even for properties with known enum constraints or boolean type — users had to type valid option strings manually.</li>
</ul>
<h4 id="summary-steps-reproduce">Steps to reproduce</h4>
<ol>
<li>Go to <code>/admin/config/ai/agents</code>.</li>
<li>edit or add an agent via Modeler or the normal configuration form.</li>
<li>Select a tool that has an enum constraint or a boolean type property.</li>
<li>Under Limits, set the action to "Force value".</li>
<li>Notice: "Force value" is not user-friendly.</li>
</ol>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
Refactored all form processors to use the new <code>PropertyLimitWidgetHelper</code> class.
<p>?</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<p>?</p>
<h3 id="summary-ui-changes">User interface changes</h3>
<p>N/A</p>
<h3 id="summary-api-changes">API changes</h3>
<p>N/A</p>
<h3 id="summary-data-model-changes">Data model changes</h3>
<p>N/A</p>
task