Serve label glyphs from the Open Waters font stack

[bkeepers]

Label glyphs come from https://tiles.openwaters.io/fonts (tile-fonts) instead of the VersaTiles glyph server.

The chart sets soundings and other hydrographic text in a sloping face (S-4 B-412.1), and VersaTiles serves no italic Noto. The style borrowed Open Sans italic for that text, and every stack name had to be mangled into versatiles' lowercase-underscore form on the way out. Seascape's next release moves its own labels to Noto Sans Medium and Medium Italic, which VersaTiles does not carry at all.

The style now asks for the stacks its layers actually name. The base map's labels follow: its bold stack asks for Noto Sans SemiBold, the heaviest weight tile-fonts publishes.

Verification

• All six published stacks return 200 with access-control-allow-origin: * and year-long immutable caching. Noto Sans Bold 404s, as expected.
• The built style asks for Regular, Italic, and SemiBold only, and no layer uses a composite stack. A new test fails if a layer ever names a stack the server does not publish.
• Rendered the viewer against the live endpoint at z13 (Aarhus) and z4 (northern Europe): chart, base map, and bathymetry labels all draw, italics are true italics, and the Cyrillic, Greek, and CJK ranges all return 200.

[Copilot]

Pull request overview

Updates the Seamap style builder and documentation so label glyphs are served from the Open Waters tile-fonts endpoint (instead of VersaTiles), enabling true italics and additional Noto weights required by the chart and upcoming Seascape label stacks.

Changes:

• Switched the whole-style builder to use https://tiles.openwaters.io/fonts/{fontstack}/{range}.pbf for glyphs, and configured the base map label font stack to use Noto Sans Regular/SemiBold.
• Removed the old VersaTiles-specific fontstack name mangling from style assembly.
• Added a regression test ensuring the built style only references font stacks published by the glyph server, and updated docs/attribution accordingly.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
style/README.md	Documents the new glyph endpoint and updates layers({ font? }) wording for the relevant Noto stacks.
style/index.ts	Points colorful() glyphs to the Open Waters font endpoint, configures base-map font stacks, and removes VersaTiles font renaming during assembly.
style/index.test.ts	Adds a test that asserts the built style only requests published font stacks and uses the expected glyph URL template.
README.md	Updates data source attribution to separate VersaTiles (base map) from Noto (glyphs).
CONTRIBUTING.md	Updates contributor documentation to reflect the new glyph source and tooling.

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