fix(app): always apply safe area insets

[Brendonovich]

Summary

• apply top and bottom safe-area insets at the V2 layout boundary
• keep both physical screen edges reserved regardless of navigation placement
• remove duplicated conditional safe-area sizing from the titlebar

Validation

• bun typecheck from packages/app
• bun run build from packages/app
• repository pre-push typecheck hook

Screenshots

Not included because desktop Chromium reports zero-valued device safe-area environment insets, so automated before/after captures would not show the affected behavior.