Add click-to-view lightbox with zoom for chat images

Tapping a chat image opens a full-screen viewer (same resolved
image source, no extra fetch) with zoom in/out buttons, mouse-wheel
zoom, drag-to-pan once zoomed, and double-click to toggle zoom.
Wheel zoom uses a native non-passive listener rather than JSX onWheel,
since a passive listener's preventDefault() is silently ignored and
would leave the page scrolling under the lightbox.

Also closes a gap the row-click-to-select change (1cc6f506) left open:
image/video/audio/file attachments inside a bubble had no selectMode
awareness, so tapping one during bulk-select would also open the
lightbox / play media / start a download alongside toggling the row.
Added a `locked` prop to all four attachment components (disabling
their own click behavior without changing how they look) and wired
`locked={selectMode}` from both MessageBubble.tsx and drafty.tsx's
IM/EX/AU/VD cases.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/features/messages/MessageBubble.tsx

@@ -239,13 +239,13 @@ export function MessageRow({
                 <ContactCardBubble content={contactCard} />
               ) : mobileAttachment ? (
                 mobileAttachment.kind === 'image' ? (
-                  <ImageAttachment data={mobileAttachment} />
+                  <ImageAttachment data={mobileAttachment} locked={selectMode} />
                 ) : mobileAttachment.kind === 'video' ? (
-                  <VideoAttachment data={{ ...mobileAttachment, previewRef: mobileAttachment.previewRef }} />
+                  <VideoAttachment data={{ ...mobileAttachment, previewRef: mobileAttachment.previewRef }} locked={selectMode} />
                 ) : mobileAttachment.kind === 'voice' ? (
-                  <AudioAttachment data={mobileAttachment} />
+                  <AudioAttachment data={mobileAttachment} locked={selectMode} />
                 ) : (
-                  <FileAttachment data={mobileAttachment} />
+                  <FileAttachment data={mobileAttachment} locked={selectMode} />
                 )
               ) : (
                 renderDrafty(msg.content, undefined, !selectMode)