fix(app): restore open folder actions

[askforoneZY]

Issue for this PR

Closes #29875

Related context-menu requests: Refs #14784, Refs #26918.

This PR intentionally keeps the scope narrow: it restores the desktop open-folder action in the V2 session header and adds the file-tree open-folder context-menu action. It does not implement the broader copy path, rename, delete, or full file-operation menu requested in #26918.

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

• Restores the V2 desktop session-header open-folder action for local desktop sessions.
• Restores the file-tree context-menu open-folder behavior for files and folders.
• Adds localized open-folder labels and keeps i18n parity coverage aligned.

How did you verify your code works?

• bun test --preload ./happydom.ts src/components/session/session-header.test.tsx from packages/app: 4 pass, 0 fail, 9 expect() calls.
• bun test --preload ./happydom.ts src/components/file-tree.test.ts from packages/app: 11 pass, 0 fail, 62 expect() calls.
• bun typecheck from the repo root: 21 successful, 21 total.

Screenshots / recordings

Browser/screenshot evidence is unavailable in this environment, so no screenshot or recording is attached.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found one potentially related PR:

PR #29888 - fix(app): add open folder button to V2 desktop session header

• fix(app): add open folder button to V2 desktop session header #29888
• This PR appears to be directly related to the current PR fix(app): restore open folder actions #30304, as both address open folder functionality in the V2 desktop session header. They may be addressing the same issue or this could be a predecessor/related attempt at the same feature.