Promote file manager terminals to tabs

[ZacharyZcR]

Summary

• add a title-bar action to file-manager terminal windows that opens the session as a normal terminal tab
• carry the terminal window's current initial path into the promoted terminal tab
• wire file-manager terminal promotion through the existing AppShell tab creation path

Verification

• npm run type-check
• npx eslint src/ui/AppShell.tsx src/ui/shell/tabUtils.tsx src/ui/features/file-manager/FileManager.tsx src/ui/features/file-manager/file-manager-types.ts src/ui/features/file-manager/components/TerminalWindow.tsx src/ui/features/file-manager/components/DraggableWindow.tsx
• npx prettier --check src/ui/AppShell.tsx src/ui/shell/tabUtils.tsx src/ui/features/file-manager/FileManager.tsx src/ui/features/file-manager/file-manager-types.ts src/ui/features/file-manager/components/TerminalWindow.tsx src/ui/features/file-manager/components/DraggableWindow.tsx
• git diff --check

Notes

• npm run build still fails before this change is reached because @fontsource/jetbrains-mono/400.css cannot be resolved from src/ui/index.css.

Fixes Termix-SSH/Support#862

[LukeGus]

@copilot resolve the merge conflicts in this pull request