perf: reduce re-renders, fix mobile keyboard handling, add chunk load recovery, and improve PATH management (#1028)

* fix: exclude file content from reverted prompt text

Revert and fork now restore only the user's original prompt, not server-injected file content
Uses existing isSyntheticPart helper for type-safe filtering

* fix: keep scrollbar visible when hovering over thumb

* fix: prevent ESC abort from triggering when terminal is focused

* fix: pass directory to permission/question reply calls so approvals actually resolve

* fix: default model selection not responding after Base UI migration

* fix: prevent modal content from shifting and clipping footer buttons

* fix: improve session switching performance and add sub-agent export with prompt collapse

Defer viewport anchor saving to eliminate ~800ms UI freeze when switching sessions
Add export dialog to include sub-agent tasks recursively in markdown export
Add collapse chevron button for expanded user prompts in sticky header

* fix: resolve sidebar scroll and TDZ crash in session sidebar

* perf: reduce CPU overhead and re-renders across chat, layout, and settings

* fix: position collapse button at top of message and prevent ESC abort in terminal

* fix: position collapse button at top and add padding only when expanded

* refactor: extract shared PATH utilities and mobile keyboard hook

* refactor: import shared path-utils in electron, use module-level style constants

- Electron now imports pathLooksUserConfigured/mergePathValues from
  shared path-utils.js instead of inline duplication
- ToolPart collapsedCustomStyle moved from useMemo([]) to module const

* fix: resolve remaining merge conflicts and type errors

- Remove duplicate variable declarations in SessionNodeItem
- Remove orphaned export callback body from conflict resolution
- Fix HelpDialog description -> descriptionKey (i18n rename)

* fix: resolve type-check and lint errors in session-actions.test.ts

- Added missing bun:test type declarations (beforeEach, mock, mock.module)
- Removed unused State import
- Replaced 'as any' casts with proper OpencodeClient and ChildStoreManager types
- Added eslint-disable for unused _ parameter in mock function

* fix PR 1028 export and PATH edge cases

* fix startup retry exhaustion state

* remove opencode package lock change

* fix sub-session rename cancellation

---------

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

packages/ui/src/components/chat/message/parts/ReasoningPart.tsx

@@ -104,7 +104,7 @@ export const ReasoningTimelineBlock: React.FC<ReasoningTimelineBlockProps> = ({
             return;
         }
         onContentChange?.('structural');
-    }, [onContentChange, isExpanded, text]);
+    }, [onContentChange, text]);
 
     if (!text || text.trim().length === 0) {
         return null;
@@ -191,11 +191,11 @@ type ReasoningPartProps = {
     messageId: string;
 };
 
-const ReasoningPart: React.FC<ReasoningPartProps> = ({
+const ReasoningPart = React.memo(({
     part,
     onContentChange,
     messageId,
-}) => {
+}: ReasoningPartProps) => {
     const chatRenderMode = useUIStore((state) => state.chatRenderMode);
     const partWithText = part as PartWithText;
     const rawText = partWithText.text || partWithText.content || '';
@@ -225,7 +225,7 @@ const ReasoningPart: React.FC<ReasoningPartProps> = ({
             isStreaming={isStreaming}
         />
     );
-};
+});
 
 // eslint-disable-next-line react-refresh/only-export-components
 export const formatReasoningText = (text: string): string => cleanReasoningText(text);