refactor(workspace): migrate from per-folder windows to single-window workspace

Replace the legacy folder + welcome routes with a unified /workspace route
that hosts all folders, conversations, tabs, and terminals in one window.

- Persist opened tabs to the database (opened_tabs entity + migration)
  so tab layout survives restarts and deep-link bootstrap restores state
- Replace FolderContext shim with AppWorkspaceProvider, ActiveFolderProvider,
  and TabProvider; expose both opened (folders) and full DB (allFolders)
  listings via list_all_folder_details
- Return conversations across all non-deleted folders from list_all when
  no folder filter is given, so the sidebar can show every folder's history
- Add ConversationContextBar above the chat input with folder picker
  (auto-opens unopened folders on select), branch picker, and commit /
  push / merge / stash entries to restore BranchDropdown functionality
- Rework sidebar with stats header, search, flat / folder-grouped view
  modes (localStorage-persisted), reveal-in-sidebar event subscriber,
  and per-folder context menu (focus, close tabs, remove from workspace);
  indent conversations under folder headers in grouped mode
- Gate terminal creation on active folder and show folder context
- Remove deprecated BranchDropdown, FolderNameDropdown, welcome route,
  and per-folder window commands
- Localize all new strings across 10 locales

src/components/tabs/tab-item.tsx

@@ -20,10 +20,14 @@ interface TabItemProps {
   tab: TabItemData
   isActive: boolean
   isTileMode: boolean
+  folderName: string | null
+  folderBranch: string | null
   onSwitch: (tabId: string) => void
   onClose: (tabId: string) => void
   onCloseOthers: (tabId: string) => void
   onCloseAll: () => void
+  onCloseFolderTabs: (folderId: number) => void
+  onRevealInSidebar: (folderId: number) => void
   onPin: (tabId: string) => void
   onToggleTile: () => void
 }
@@ -32,10 +36,14 @@ export const TabItem = memo(function TabItem({
   tab,
   isActive,
   isTileMode,
+  folderName,
+  folderBranch,
   onSwitch,
   onClose,
   onCloseOthers,
   onCloseAll,
+  onCloseFolderTabs,
+  onRevealInSidebar,
   onPin,
   onToggleTile,
 }: TabItemProps) {
@@ -43,6 +51,19 @@ export const TabItem = memo(function TabItem({
   const isDragging = useRef(false)
   const itemRef = useRef<HTMLDivElement>(null)
 
+  const resolvedFolderName = folderName ?? String(tab.folderId)
+  const tooltip = folderBranch
+    ? `${resolvedFolderName} · ${folderBranch}  —  ${tab.title}`
+    : `${resolvedFolderName}  —  ${tab.title}`
+
+  const handleCloseFolderTabs = useCallback(() => {
+    onCloseFolderTabs(tab.folderId)
+  }, [onCloseFolderTabs, tab.folderId])
+
+  const handleRevealInSidebar = useCallback(() => {
+    onRevealInSidebar(tab.folderId)
+  }, [onRevealInSidebar, tab.folderId])
+
   const clearResidualStyles = useCallback(() => {
     const el = itemRef.current
     if (!el) return
@@ -119,7 +140,7 @@ export const TabItem = memo(function TabItem({
                 "truncate max-w-[140px]",
                 !tab.isPinned && "[font-style:oblique]"
               )}
-              title={tab.title}
+              title={tooltip}
             >
               {tab.title}
             </span>
@@ -146,7 +167,13 @@ export const TabItem = memo(function TabItem({
           <ContextMenuItem onSelect={handleCloseOthers}>
             {t("closeOthers")}
           </ContextMenuItem>
+          <ContextMenuItem onSelect={handleCloseFolderTabs}>
+            {t("closeFolderTabs", { folder: resolvedFolderName })}
+          </ContextMenuItem>
           <ContextMenuSeparator />
+          <ContextMenuItem onSelect={handleRevealInSidebar}>
+            {t("revealInSidebar")}
+          </ContextMenuItem>
           <ContextMenuItem onSelect={onToggleTile}>
             {isTileMode ? t("untileDisplay") : t("tileDisplay")}
           </ContextMenuItem>