feat(ui): revert indicator with undo/redo, message list, and attachment restore (#1279)

* feat(ui): revert indicator with undo/redo, message list, and attachment restore

Add bidirectional undo/redo with redo stack navigation and expandable
revert indicator in StatusRow. List reverted messages with inline
revert/fork actions. Restore file attachments on revert.

- Add revert indicator with count, expandable popover, per-button spinner
- Restore file/image attachments when reverting to a message
- Clear previous attachments on revert when target has none
- Restore-all bypasses redo stack for direct unrevert
- Survive popover close/reopen without losing loading state
- Fix flash when sending message after revert
- Fix count disappearing on browser refresh
- Remove dead code (undoStack, getRevertHistory, fork-from-here)
- Fix toast grammar (Undid -> Reverted, Redid -> Redone)
- Add i18n keys for revert popover across all locales

* fix(ui): Greptile review fixes and i18n for revert toasts

- Fix handleSlashUndo toast always showing [No text] (moved getSyncParts before revertToMessage)
- Add inputStore rollback in revertToMessage catch (restore attachments + text on API failure)
- Change portal ID to per-session (prevent multi-session collisions)
- Add i18n keys for undo/redo/restored toasts across all 7 locales
- Use formatMessage in store for localized toast strings

* fix(ui): add missing sessionId to click-outside effect deps

* fix(ui): remove unused sessionActions import in ChatMessage

* fix(ui): derive revert dock from session state

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/sync/input-store.ts

@@ -86,6 +86,8 @@ export type InputState = {
   addVSCodeFileAttachment: (path: string, name: string, fileSize: number | null) => void
   addVSCodeSelectionAttachment: (path: string, file: File) => Promise<void>
   setActiveEditorFile: (file: VSCodeActiveEditorFile | null) => void
+  /** Add attachments restored from a reverted message (file already on server) */
+  addRestoredAttachment: (file: { url: string; mimeType: string; filename: string }) => void
 }
 
 export const useInputStore = create<InputState>()((set, get) => ({
@@ -210,4 +212,23 @@ export const useInputStore = create<InputState>()((set, get) => ({
     if (isSameVSCodeActiveEditorFile(get().activeEditorFile, file)) return
     set({ activeEditorFile: file })
   },
+
+  addRestoredAttachment: ({ url, mimeType, filename }) => {
+    const id = `restored-${Date.now()}-${Math.random().toString(36).slice(2)}`
+    // Use "local" source so the file renders in AttachedFilesList.
+    // Set serverPath to the URL so ImagePreview can use it as the img src
+    // when dataUrl is not a data: URL. sanitizeAttachmentsForSend leaves
+    // dataUrl alone for non-server sources, so the URL stays intact on send.
+    const attached: AttachedFile = {
+      id,
+      file: new File([], filename, { type: mimeType }),
+      dataUrl: url,
+      mimeType,
+      filename,
+      size: 0,
+      source: "local",
+      serverPath: url,
+    }
+    set((s) => ({ attachedFiles: [...s.attachedFiles, attached] }))
+  },
 }))