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>

translate.php

@@ -68,7 +68,7 @@ $ltI18n = [
                     <div id="docPickerSection" class="doc-picker-section">
                         <button type="button" id="docPickerBtn" class="doc-picker-btn" aria-haspopup="dialog">
                             <svg class="doc-picker-btn__icon" width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true"><rect x="2" y="1" width="9" height="12" rx="1.5" stroke="currentColor" stroke-width="1.4"/><path d="M5 5h5M5 8h3" stroke="currentColor" stroke-width="1.3" stroke-linecap="round"/><rect x="7" y="9" width="6" height="5" rx="1" fill="white" stroke="currentColor" stroke-width="1.3"/><path d="M9 11h2M9 12.5h1" stroke="currentColor" stroke-width="1" stroke-linecap="round"/></svg>
-                            <span>Select from My Docs</span>
+                            <span><?= htmlspecialchars($ltT('doc_picker_btn')) ?></span>
                         </button>
                         <div id="docPickerChips" class="doc-picker-chips" aria-label="Selected documents"></div>
                         <input type="hidden" id="docPickerIds" name="doc_ids" value="">