[Design P2] Enforce minimum font size >=12px across all UI components

[AnilChinchawaleXDC]

Source: DESIGN-AUDIT.md

Problem: section-header is 11px, badge text is 10px, dock labels are 9px — all below 12px minimum.

Actions:

1. Audit all font-size usages in codebase
2. Increase section-header to 12px minimum
3. Increase badge text to 12px
4. Increase dock labels to 12px
5. Add lint rule or design token enforcement

Risk: Accessibility issues, poor readability.

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Mirrored from Paperclip OPEA-369 (https://agi.openscan.ai/OPEA/issues/OPEA-369)