feat(chat): render Media/Files + Group Info drawers inline, not overlaid

Both right-hand panels used absolute inset-y-0 right-0 and floated on
top of the conversation, hiding the messages directly underneath the
panel and looking unlike Discord's actual layout. Restructure:

* MediaFilesDrawer: drop absolute/z-index/shadow chrome, become a
  static flex column (w-[380px] shrink-0) with a left border. Internal
  layout unchanged.
* GroupInfoPanel: same treatment (w-[320px] shrink-0). Dropped the
  backdrop-blur and slide-up animation that only made sense as a modal.
* ConversationPage: wrap the chat content (voice rail, in-call panel,
  messages list, drag-overlay, input form) in a new
  `flex min-w-0 flex-1 flex-col` chat-column, and make that column a
  sibling of the drawers inside a new `flex flex-1 flex-row` row. The
  conversation header + search bar stay full-width above the row.

Result: opening a drawer narrows the chat column instead of covering
it, matching Discord's behaviour. The chat-column wrapper also carries
the `relative` anchor previously held by the outer wrapper so the
drag-and-drop overlay positions correctly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop/src/pages/ConversationPage.tsx

@@ -643,31 +643,19 @@ export function ConversationPage() {
         />
       )}
 
-      {isGroup && conversation && (
-        <GroupInfoPanel
-          open={infoPanelOpen}
-          onClose={() => setInfoPanelOpen(false)}
-          conversation={conversation}
-        />
-      )}
-
-      <MediaFilesDrawer
-        open={mediaDrawerOpen}
-        index={attachmentIndex}
-        senderNameFor={senderNameFor}
-        onJumpToMessage={(messageId) => {
-          setMediaDrawerOpen(false);
-          jumpToMessage(messageId);
-        }}
-        onClose={() => setMediaDrawerOpen(false)}
-      />
-
-      {/* Discord-style persistent voice-channel rail. Always visible in groups
-          so anyone can pop in without an invite-ring; hidden in 1:1s unless
-          someone is already waiting. Hides automatically once we're in. */}
-      {conversation && !incomingHere && <VoiceChannelRail conversation={conversation} />}
-      {incomingHere && conversation && <IncomingCallPanel conversation={conversation} />}
-      {conversation && <InCallPanel conversation={conversation} />}
+      {/* Layout row: chat column on the left grows to fill remaining width;
+          right-hand drawers (Media/Files, Group Info) render as inline
+          siblings so opening one narrows the chat instead of floating on
+          top of it (Discord parity). The chat-column wrapper holds the
+          `relative` anchor for the drag-and-drop overlay further below. */}
+      <div className="flex min-h-0 flex-1 flex-row">
+        <div className="relative flex min-w-0 flex-1 flex-col">
+          {/* Discord-style persistent voice-channel rail. Always visible in groups
+              so anyone can pop in without an invite-ring; hidden in 1:1s unless
+              someone is already waiting. Hides automatically once we're in. */}
+          {conversation && !incomingHere && <VoiceChannelRail conversation={conversation} />}
+          {incomingHere && conversation && <IncomingCallPanel conversation={conversation} />}
+          {conversation && <InCallPanel conversation={conversation} />}
 
       <div
         ref={scrollRef}
@@ -1019,6 +1007,27 @@ export function ConversationPage() {
           </button>
         </div>
       </form>
+        </div>
+
+        {isGroup && conversation && (
+          <GroupInfoPanel
+            open={infoPanelOpen}
+            onClose={() => setInfoPanelOpen(false)}
+            conversation={conversation}
+          />
+        )}
+
+        <MediaFilesDrawer
+          open={mediaDrawerOpen}
+          index={attachmentIndex}
+          senderNameFor={senderNameFor}
+          onJumpToMessage={(messageId) => {
+            setMediaDrawerOpen(false);
+            jumpToMessage(messageId);
+          }}
+          onClose={() => setMediaDrawerOpen(false)}
+        />
+      </div>
 
       <ForwardDialog
         open={forwardTarget !== null}