Add document upload to Redact tool

api/extract.php — new endpoint accepting .pdf/.docx/.txt up to 4 MB;
pdftotext for PDFs, ZipArchive+DOMXPath for DOCX, mb_convert_encoding
for TXT; truncates to 32 000 chars to stay within redact limit.

index.php — drop/browse upload zone above the textarea, visible only
in Redact mode.

tools.js — setupUpload(), handleFileUpload(), resetUpload(); drag-and-drop
and file picker both call the extract endpoint then populate the textarea.

tools.css — upload zone, drag-over, file-info, clear button styles.

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

assets/css/tools.css

@@ -873,3 +873,93 @@ p {
   overflow-x: auto;
   color: #374151;
 }
+
+/* ─── Upload zone (Redact tool) ──────────────────────────────────────────── */
+
+.upload-zone {
+  border: 2px dashed var(--line);
+  border-radius: 8px;
+  padding: 18px 14px;
+  text-align: center;
+  cursor: pointer;
+  transition: border-color 0.15s, background 0.15s;
+  position: relative;
+}
+
+.upload-zone:hover {
+  border-color: var(--teal);
+  background: #f7fdfb;
+}
+
+.upload-zone.is-drag-over {
+  border-color: var(--teal);
+  background: var(--soft-teal);
+}
+
+#uploadInput {
+  position: absolute;
+  width: 0;
+  height: 0;
+  opacity: 0;
+  pointer-events: none;
+}
+
+.upload-icon {
+  display: block;
+  font-size: 1.8rem;
+  line-height: 1;
+  color: var(--teal);
+  opacity: 0.55;
+  margin-bottom: 6px;
+}
+
+.upload-prompt p {
+  margin: 4px 0 0;
+  color: var(--muted);
+  font-size: 0.88rem;
+}
+
+.upload-browse {
+  color: var(--teal);
+  font-weight: 700;
+  cursor: pointer;
+  text-decoration: underline;
+  text-underline-offset: 2px;
+}
+
+.upload-hint {
+  font-size: 0.76rem !important;
+  opacity: 0.7;
+}
+
+.upload-file {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 10px;
+  min-height: 48px;
+}
+
+.upload-filename {
+  font-size: 0.88rem;
+  font-weight: 600;
+  color: var(--ink);
+  word-break: break-all;
+}
+
+.upload-clear {
+  flex-shrink: 0;
+  background: transparent;
+  color: var(--muted);
+  font-size: 1.25rem;
+  line-height: 1;
+  padding: 2px 7px;
+  border-radius: 4px;
+  border: 1px solid transparent;
+}
+
+.upload-clear:hover {
+  background: var(--soft-coral);
+  color: var(--coral);
+  border-color: #f5c6aa;
+}