feat: add font size controls to view template

[hhhjin]

Summary

• add explicit font size controls to the shared view template top actions
• wire the controls into the generated client-side script and theme CSS
• update the template test coverage and regenerate the template hash

Testing

• pnpm test -- --run shared/templates/tests/view.template.spec.tsx

[gemini-code-assist]

Code Review

This pull request introduces font size controls to the view template, allowing users to adjust text size via UI buttons or keyboard shortcuts. The changes include new CSS styles for the controls across multiple themes, a new FontSizeControls component, and client-side logic for font size manipulation. Feedback suggests improving the initialization of the font size index by detecting the actual computed style to avoid unexpected jumps and reconsidering the use of standard browser zoom shortcuts to prevent interference with native accessibility features.