fix(media viewer): lightbox focuses itself on open (keys worked only after a click); timeline viewer gets +/-/0 keys, double-click zoom and dialog semantics (#164)

Gallery lightbox: FocusTrap had initialFocus:false, so focus stayed on the
tile behind the overlay and ←/→/Esc/+/- were dead until the user clicked
inside. Timeline ImageViewer: no keyboard zoom, no role/aria-modal/label,
focus landed on the <img>; now mirrors the lightbox (+ = / - / 0,
double-click toggles 1×↔2×, role=dialog aria-modal labelled by the file
name, focuses on open).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/image-viewer/ImageViewer.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useEffect, useRef } from 'react';
 import { useTranslation } from 'react-i18next';
 import classNames from 'classnames';
 import { Box, Chip, Header, Icon, IconButton, Icons, Text, as } from 'folds';
@@ -27,12 +27,37 @@ export const ImageViewer = as<'div', ImageViewerProps>(
       saveFile(fileContent, alt);
     };
 
+    // [Gitea #164] Same keyboard model as the gallery lightbox: + / = zoom
+    // in, - zoom out, 0 reset; double-click toggles 1× ↔ 2×. The root takes
+    // focus on open so those keys (and Escape, handled by the modal) work
+    // immediately instead of only after clicking inside the viewer.
+    const rootRef = useRef<HTMLDivElement>(null);
+    useEffect(() => {
+      rootRef.current?.focus({ preventScroll: true });
+    }, []);
+    const handleKeyDown = (evt: React.KeyboardEvent) => {
+      if (evt.key === '+' || evt.key === '=') zoomIn();
+      else if (evt.key === '-') zoomOut();
+      else if (evt.key === '0') setZoom(1);
+      else return;
+      evt.preventDefault();
+    };
+
     return (
       <Box
         className={classNames(css.ImageViewer, className)}
         direction="Column"
+        role="dialog"
+        aria-modal
+        aria-label={alt || 'Image viewer'}
+        tabIndex={-1}
+        onKeyDown={handleKeyDown}
         {...props}
-        ref={ref}
+        ref={(node: HTMLDivElement | null) => {
+          rootRef.current = node;
+          if (typeof ref === 'function') ref(node);
+          else if (ref) (ref as React.MutableRefObject<HTMLDivElement | null>).current = node;
+        }}
       >
         <Header className={css.ImageViewerHeader} size="400">
           <Box grow="Yes" alignItems="Center" gap="200">
@@ -116,6 +141,7 @@ export const ImageViewer = as<'div', ImageViewerProps>(
             alt={alt}
             onMouseDown={onMouseDown}
             onTouchStart={onTouchStart}
+            onDoubleClick={() => setZoom(zoom === 1 ? 2 : 1)}
           />
         </Box>
       </Box>

src/app/features/room/MediaGallery.tsx

@@ -302,6 +302,7 @@ function Lightbox({
   // Pan is only active for a zoomed-in image; usePan resets its offset when this
   // flips false (i.e. back to 1x, on navigation, or on a video).
   const { pan, cursor, onMouseDown, onTouchStart } = usePan(isImage && zoom !== 1);
+  const dialogRef = useRef<HTMLDivElement>(null);
   const toggleZoom = useCallback(() => setZoom((z) => (z === 1 ? 2 : 1)), [setZoom]);
 
   // Reset zoom when navigating to another item (and thus pan, via usePan).
@@ -346,12 +347,17 @@ function Lightbox({
     <Overlay open backdrop={<OverlayBackdrop />}>
       <FocusTrap
         focusTrapOptions={{
-          initialFocus: false,
+          // Focus the dialog itself on open: with `initialFocus: false` focus
+          // stayed on the gallery tile behind the overlay, so ←/→/Esc/+/-
+          // (handled by onKeyDown below) did nothing until the user clicked
+          // inside the viewer (Gitea #164).
+          initialFocus: () => dialogRef.current ?? false,
           clickOutsideDeactivates: false,
           escapeDeactivates: false,
         }}
       >
         <div
+          ref={dialogRef}
           role="dialog"
           aria-modal
           aria-label="Media viewer"