Increase zoom-driven dynamic point sizing

[lhawkman27]

Small dynamically sized map points need stronger growth as users zoom in. Increase the zoom multiplier above zoom 4 from 0.25 to 1 per zoom level, with an 8x cap instead of 3.5x. The configured point size remains unchanged through zoom 4, and invalid zoom values still fall back to 1x.

This ports only the point-sizing increase merged in GitLab MR !117 (source commit 5f7f736). The earlier point-sizing implementation is already in GeoSet via #381.

Updated examples: zoom 6 = 3x, zoom 8 = 5x, maximum = 8x.

Validation:

• Updated existing unit test expectations for growth and the cap.
• Both changed files match the merged GitLab main versions exactly.
• git diff --check passed; only the sizing helper and its test change.
• Jest was not run locally because Node and frontend dependencies are unavailable.