Add Deep Research tool — agent + rank/rerank RAG

New surface at /deep-research.php where the user pastes a question or
uploads PDF/DOCX/TXT case files and a LLM-orchestrated agent researches
the Do Better Norge legal corpus from 3-5 angles, with hybrid retrieval,
cross-encoder rerank, and synthesis that emits an inline-[n]-cited
markdown brief plus a numbered sources panel.

Uploaded documents are chunked + embedded in memory only (nomic-embed-text
via LiteLLM) and searched alongside the shared corpus during the same
request — never persisted to disk, DB, or Qdrant.

Reuses ClientRagPipeline::searchAll (hybrid + rerank), dbnV6 slice
helpers, and the existing extract.php text-extraction logic via a new
dbnToolsExtractUploadedFile() helper. Also adds dbnToolsCallGpuLlm()
helper in bootstrap.php — fixes a latent bug where LegalTools.php
was already calling that name with no definition.

Search.php is unchanged.

api/extract.php

@@ -6,132 +6,16 @@ require_once __DIR__ . '/../includes/bootstrap.php';
 dbnToolsRequireMethod('POST');
 dbnToolsRequireAuth();
 
-const EXTRACT_MAX_BYTES = 4 * 1024 * 1024;
-const EXTRACT_TEXT_LIMIT = 128000;
-const EXTRACT_ALLOWED_EXTS = ['txt', 'pdf', 'docx'];
-
 try {
     if (empty($_FILES['file']) || !is_array($_FILES['file'])) {
         dbnToolsError('No file was uploaded.', 422, 'missing_file');
     }
 
-    $file    = $_FILES['file'];
-    $errCode = (int)($file['error'] ?? UPLOAD_ERR_NO_FILE);
-
-    if ($errCode !== UPLOAD_ERR_OK) {
-        $msg = match ($errCode) {
-            UPLOAD_ERR_INI_SIZE, UPLOAD_ERR_FORM_SIZE => 'The file exceeds the allowed size limit.',
-            UPLOAD_ERR_NO_TMP_DIR => 'No temporary directory is available.',
-            UPLOAD_ERR_CANT_WRITE => 'Unable to save the uploaded file.',
-            default => 'File upload failed.',
-        };
-        dbnToolsError($msg, 422, 'upload_error');
-    }
-
-    $originalName = basename((string)($file['name'] ?? ''));
-    $tmpPath      = (string)($file['tmp_name'] ?? '');
-    $size         = (int)($file['size'] ?? 0);
-
-    if (!is_uploaded_file($tmpPath)) {
-        dbnToolsError('Invalid file upload.', 400, 'invalid_upload');
-    }
-    if ($size === 0) {
-        dbnToolsError('The uploaded file is empty.', 422, 'file_empty');
-    }
-    if ($size > EXTRACT_MAX_BYTES) {
-        dbnToolsError('File exceeds the 4 MB limit.', 413, 'file_too_large');
-    }
-
-    $ext = strtolower(pathinfo($originalName, PATHINFO_EXTENSION));
-    if (!in_array($ext, EXTRACT_ALLOWED_EXTS, true)) {
-        dbnToolsError('Unsupported file type. Upload a .pdf, .docx, or .txt file.', 422, 'unsupported_type');
-    }
-
-    $text = match ($ext) {
-        'txt'  => extractTxt($tmpPath),
-        'pdf'  => extractPdf($tmpPath),
-        'docx' => extractDocx($tmpPath),
-    };
-
-    $text = trim($text);
-    if ($text === '') {
-        dbnToolsError('No text could be extracted from this file.', 422, 'no_text');
-    }
-
-    $truncated = false;
-    if (mb_strlen($text, 'UTF-8') > EXTRACT_TEXT_LIMIT) {
-        $text      = mb_substr($text, 0, EXTRACT_TEXT_LIMIT, 'UTF-8');
-        $truncated = true;
-    }
-
-    dbnToolsRespond([
-        'ok'        => true,
-        'text'      => $text,
-        'filename'  => $originalName,
-        'chars'     => mb_strlen($text, 'UTF-8'),
-        'truncated' => $truncated,
-    ]);
+    $result = dbnToolsExtractUploadedFile($_FILES['file']);
+    dbnToolsRespond($result);
 } catch (DbnToolsHttpException $e) {
     dbnToolsError($e->getMessage(), $e->status, $e->errorCode, $e->extra);
 } catch (Throwable $e) {
     error_log('DBN extract error: ' . $e->getMessage());
     dbnToolsError('Text extraction failed.', 500, 'extract_error');
 }
-
-function extractTxt(string $path): string
-{
-    $content = file_get_contents($path);
-    if ($content === false) {
-        throw new DbnToolsHttpException('Unable to read the file.', 500, 'read_error');
-    }
-    return mb_convert_encoding($content, 'UTF-8', 'UTF-8, ISO-8859-1, Windows-1252');
-}
-
-function extractPdf(string $path): string
-{
-    $cmd    = 'pdftotext ' . escapeshellarg($path) . ' - 2>/dev/null';
-    $output = shell_exec($cmd);
-    if ($output === null || $output === false || trim($output) === '') {
-        throw new DbnToolsHttpException(
-            'PDF text extraction failed. The file may be image-only or encrypted.',
-            422,
-            'pdf_extract_failed'
-        );
-    }
-    return $output;
-}
-
-function extractDocx(string $path): string
-{
-    $zip    = new ZipArchive();
-    $result = $zip->open($path);
-    if ($result !== true) {
-        throw new DbnToolsHttpException('Unable to open the .docx file.', 422, 'docx_open_failed');
-    }
-
-    $xml = $zip->getFromName('word/document.xml');
-    $zip->close();
-
-    if ($xml === false) {
-        throw new DbnToolsHttpException('No document content found in this .docx file.', 422, 'docx_no_content');
-    }
-
-    $doc = new DOMDocument();
-    libxml_use_internal_errors(true);
-    $doc->loadXML($xml);
-    libxml_clear_errors();
-
-    $xpath = new DOMXPath($doc);
-    $xpath->registerNamespace('w', 'http://schemas.openxmlformats.org/wordprocessingml/2006/main');
-
-    $paragraphs = [];
-    foreach ($xpath->query('//w:p') as $para) {
-        $runs = [];
-        foreach ($xpath->query('.//w:t', $para) as $t) {
-            $runs[] = $t->textContent;
-        }
-        $paragraphs[] = implode('', $runs);
-    }
-
-    return implode("\n", $paragraphs);
-}