Simplify nested tag layout

[Clearner1]

What changed

• remove the decorative oval from tag rows while preserving pin controls and pinned tags
• remove duplicate computed indentation and use one 12px nesting step
• keep tag names on one line with ellipsis and expose the full path as a title
• make browser favicon and in-app logo assets transparent
• preserve the existing warm-white Apple touch and PWA PNG assets
• bump icon references to refresh cached branding

Root cause

Nested tag rows accumulated both recursive container margins and depth-based inline padding. A fourth-level child therefore lost enough horizontal space to wrap Chinese text vertically.

Validation

• npm run check
• 9 test files / 38 tests passed
• focused tag and icon assertions passed
• all eight brand assets are present in the production build
• transparent 32px favicon and opaque Apple touch icon visually inspected