resolution independent display (support 4k scaling)

[kylerisse]

Description of PR

Frontend react-display scales cleanly across 16:9 resolutions, upgrades sponsor logo assets to match, and bumps the Go/npm/nix toolchains. Clean up react components to pass stricter linting and just better state management in general.

A live version of this version can be viewed at https://signs.scalenoc.org - running off this commit currently kylerisse/nixcfg@master...kr/20260827011449

Previous Behavior

• Didn't look great at any resolution other than 1080p
• Older versions of dependencies

New Behavior

• Root font size is now calc(100vh / 67.5) (16px at 1080p), so every rem-based Tailwind utility scales proportionally with viewport height.
• Sponsor logos regenerated at 440×440 (was 220×220) so they still look good at higher resolutions.
• scripts/update_sponsors.sh updated and manager_test.go adjusted for the new dimensions.
• README updated to describe 16:9 resolution independence (non-16:9 aspect ratios remain unsupported).
• npm dependency bumps: React 19.2, Vite 8, TypeScript 6, ESLint 10, eslint-plugin-react-hooks 7, Tailwind 4.3.
• Go modules and nixpkgs bumped; net.Dialer.Dial → DialContext to clear a deprecation warning.

To pass stricter linting after npm bumps

• TimeProvider: compute the URL time offset once and lazy-initialize clock state.
• Clock: render from TimeContext directly instead of mirroring it into local state.
• SponsorProvider / SponsorBanner / SponsorItem: fetch the sponsor list inside the mount effect, working cross-fade without setState in effects; drops the unused refreshSponsors from the context API.
• ScheduleProvider / ScheduleCarousel: run the refresh loop inside the effect; getCurrentAndUpcomingSessions now takes now: Date so the carousel list is derived from the shared clock rather than internal state; drops refreshSchedule from the context API.

Tests

• Visually verified at 720p, 1080p, 1440p, and 4K.

[sarcasticadmin]

@kylerisse this looks great!

Confirming on my own system 2560x1080 21:9 (which I realize is outside the 16:9 expectation). No 4K atm but overall is still renderers nicely:

$ make ci-test
$ ./result/scale-signs-linux-amd64 -port 8080 -refresh 10

Utilizing the time shift http://127.0.0.1:8080/??year=2026&month=3&day=7&hour=10

[sarcasticadmin]

Phanton Phreak looking good

[sarcasticadmin]

🚀