fix(editor): reduce horizontal rule click dead zone

[murongg]

Summary

• Reduce horizontal rule vertical spacing in the WYSIWYG editor.
• Limit the horizontal-rule gap guard to the small area closest to the divider so the surrounding whitespace is less likely to feel dead.
• Update regression coverage for the narrower protected click zone and the adjusted rule spacing.

Why

#326 stopped caret jumps around horizontal rules by ignoring clicks in the rule margin. In practice that made a large area around dividers feel unresponsive. This keeps the anti-jump protection near the divider while making the surrounding whitespace less hostile to normal clicking.

Validation

• pnpm --filter @markra/app exec vitest run src/components/MarkdownPaper.test.tsx -t "horizontal rule" passed: 4 tests.
• pnpm --filter @markra/app exec vitest run src/styles.test.ts passed: 34 tests.
• pnpm --filter @markra/editor build passed.
• pnpm --filter @markra/app build passed.
• git diff --check passed.

Risk

• Low. The change is scoped to horizontal rule spacing and the existing horizontal-rule gap guard.
• The issue should stay open until users can try the next build and confirm whether the interaction feels better.

Related Issues

• Refs [Editor]: 输入光标定位不太准的后续 #331. Keep the issue open while waiting for user feedback on a new version.

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Project	Deployment	Actions	Updated (UTC)
markra-web	Ready	Preview, Comment	Jun 19, 2026 2:43am