Fix a couple more color/theme things

[micahmo]

This PR fixes two more color issues

• The modlog status bar (same fix as Fix the status bar color on the post page #1630 and Fix status bar color #1615)
  • This appears to be the last case of SafeArea.top being determined by the hideTopBarOnScroll setting, so hopefully we're done with these fixes.
  • I also allowed the SafeArea to go under the bottom nav bar, which makes the app feel more edge-to-edge, and also matches the post/comment page.
• The create post/comment page nav bar
  • Pretty similar fix here. I allowed the SafeArea to go under the nav bar and added a Container with the same background color as the MarkdownToolbar to fill the space. I verified that opening the keyboard only causes the toolbar to jump up and not the extra container.

[hjiangsu]

LGTM!