fix: remove browser-native required validation blocking doc picker submissions

Forms lacked novalidate and textareas had required, so the browser fired
HTML5 validation before tools.js could intercept — blocking submissions
where text came from the doc picker or file upload rather than the textarea.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

includes/tool_form.php

@@ -1,4 +1,4 @@
-                <form id="toolForm" class="tool-form">
+                <form id="toolForm" class="tool-form" novalidate>
                     <div class="control-row" id="languageControl">
                         <span class="control-label">Language</span>
                         <label><input type="radio" name="language" value="en" checked> English</label>
@@ -82,7 +82,7 @@
                     </div>
 
                     <label class="input-label" for="toolInput" id="inputLabel">Question</label>
-                    <textarea id="toolInput" name="toolInput" rows="10" required></textarea>
+                    <textarea id="toolInput" name="toolInput" rows="10"></textarea>
 
                     <div class="form-footer">
                         <p id="toolStatus" class="form-status" role="status" aria-live="polite"></p>