Fix docPickerBtn/audioPickerBtn i18n — add missing translation keys

Add doc_picker_btn/audio_picker_btn to i18n.php (en/no/uk/pl), add
docPickerBtn to REDACT_I18N + TIMELINE_I18N and audioPickerBtn to
TRANSCRIBE_I18N in tools.js. PHP-render picker labels in legal-analysis,
translate, summarize, tool_form, and layout_footer using dbnToolsT().

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

includes/tool_form.php

@@ -75,7 +75,7 @@
                     <div id="docPickerSection" class="doc-picker-section">
                         <button type="button" id="docPickerBtn" class="doc-picker-btn" aria-haspopup="dialog">
                             <svg class="doc-picker-btn__icon" width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true"><path d="M3 2h7l3 3v9H3V2z" stroke="currentColor" stroke-width="1.4" stroke-linejoin="round"/><path d="M10 2v3h3" stroke="currentColor" stroke-width="1.4" stroke-linejoin="round"/><path d="M5 7h6M5 9.5h4" stroke="currentColor" stroke-width="1.2" stroke-linecap="round"/></svg>
-                            <span>Select from My Docs</span>
+                            <span><?= htmlspecialchars(dbnToolsT('doc_picker_btn', $uiLang)) ?></span>
                         </button>
                         <div id="docPickerChips" class="doc-picker-chips" aria-label="Selected documents"></div>
                         <input type="hidden" id="docPickerIds" name="doc_ids" value="">