fix(web): clarify settings visual hierarchy

[techotaku39]

Summary

• establish a consistent typography hierarchy across settings sections, rows, choice groups, custom controls, and voice controls
• remove redundant desktop category headings while preserving responsive page titles and a semantic page heading
• normalize settings-card spacing, composer-toolbar insets, and the duplicated appearance label

Responsive behavior

• mobile keeps an 18px page title and divider, with 16px section headings and 14px setting labels
• desktop uses the persistent category navigation instead of repeating each category title and reserves symmetric scrollbar gutters to prevent horizontal shifts between pages

Compatibility

• independent of feat(web): add configurable tool grouping mode #1157; if both PRs are merged, its tool-grouping option will inherit the normalized shared choice-group styling

Testing

• bun typecheck
• bun run test:web
• bun run build:web
• bun run test:cli
• bun run test:shared
• git diff --check origin/main...HEAD

[github-actions]

Findings
None.

Summary
Review mode: initial
No issues found in the added/modified lines. Residual risk: visual hierarchy changes were reviewed from diff/source only; no browser screenshot pass was run here.

Testing
Ran git diff --check origin/main...HEAD. Not run: typecheck or test suites (automation review).

HAPI Bot