fix(app): complete shared RTL primitives

[opencode-agent]

Summary

• provide the selected app locale to Kobalte so dropdown/submenu placement and keyboard direction follow RTL
• anchor legacy and V2 toast regions to logical inline-end
• mirror the Tabs help popup and drawer edge for RTL
• mark and centrally mirror only shared left/right chevrons
• use logical Drawer positioning and direction-aware titlebar translation
• keep dialogs/settings page structure unchanged; no copy or translation changes

Validation

• App, UI, Session UI, and Enterprise typechecks passed
• UI tests: 27 passed
• Session UI tests: 78 passed
• App browser tests: 41 passed
• real-app visual smoke at 1400 × 900:
  • English LTR baseline
  • Arabic RTL baseline, settings dialog, dropdown, Tabs popup, and help drawer
  • Urdu RTL mixed-script baseline
• verified Arabic popup/drawer anchor left, dropdown placement follows RTL, directional chevrons mirror, and English remains unchanged
• git diff --check

Compared refs

• before: edc8d1d91e
• after: cce681f74c

Requested by: @Hona (Luke Parker via Slack)