Audit font-loading strategy to fix layout shift (CLS)

PageSpeed Insights reports a Cumulative Layout Shift of 0.28 on a site, well past the
0.1 "good" threshold. The Experience section points at heading text shifting position
right after page load.

STACK: [Elementor page builder, custom typography set to Montserrat via Elementor's
Site Settings, Google Fonts loaded via Elementor's default @import method rather than
self-hosted, no font-display value set]
OBSERVATION: [headings visibly render in a fallback serif font first, then snap to
Montserrat about half a second later, which is the actual shift being measured]

Reason through this as a consultant fixing CLS specifically, not general speed advice:
1. Confirm the font swap is the actual cause of this specific CLS number given the
   observation, and explain the mechanism: no font-display value means the browser
   either blocks rendering or swaps abruptly once the font downloads, and if the
   fallback and Montserrat have different average character widths, headings reflow.
2. Give the first fix: setting font-display: swap (or optional) on the @font-face
   rule, which stops invisible text but doesn't fully stop the shift, so name this as
   a partial fix, not the complete answer.
3. Give the deeper fix: self-hosting the font files instead of loading from Google's
   CDN, which removes a DNS/connection round trip and lets font preloading work
   reliably, plus using a fallback font stack with matching size-adjust or a similar
   font metric so the swap causes less visible reflow.
4. Note the Elementor-specific risk: self-hosting the font means it can't be managed
   through Elementor's Site Settings font picker anymore, so document that this needs
   a custom CSS or child-theme approach, and that anyone updating fonts later through
   the visual UI won't know to also update the self-hosted files.
5. Distinguish what's fixable from wp-admin (adding font-display via a plugin like
   Asset CleanUp, or Elementor's own settings if a next version exposes this) from
   what needs actual file/theme access (uploading font files, writing @font-face
   rules), since not every site has FTP or child-theme editing available.