fix: Pass Google Fonts fontspector QA for the variable font

[psd-coder]

Overview

Brings Martian Grotesk into compliance with Google Fonts QA by resolving the failures reported by fontspector (GF profile), and adds the tooling to run those checks. Covers undrawn Cyrillic glyphs, STAT weight-axis values, master/style naming, and export hygiene.

Problem Statement

The variable font did not pass Google Fonts' automated QA (fontspector, GF profile), which blocks submission to Google Fonts. The notable failures:

• Empty glyphs (contour_count / no-contour): several Cyrillic letters (Ө, Ӫ, ө, ӫ, Ӛ, ӛ, ə and related) carried Unicode codepoints but had no contours.
• STAT compulsory axis values: SemiBold (600) is a registered GF weight that falls inside the font's wght range, so it must be labeled in the STAT table; conversely UltraBlack (1000) is not in the GF Axis Registry and shouldn't be there.
• Naming: master/style names used a "Normal" prefix that conflicts with GF naming recommendations.
• No repeatable way to run the QA checks locally, so regressions were easy to miss.

Solution Approach

• Drew the missing Cyrillic glyphs (Ө/Ӫ capitals, ө/ӫ/ӛ/ə lowercase and relatives) in the Glyphs source, giving the previously-empty codepoints real outlines and clearing the no-contour failures.
• Removed smart-component parts from exports so internal helper glyphs no longer ship as empty glyphs in the final font.
• Corrected the STAT wght axis values: added SemiBold (600), removed UltraBlack (1000). SemiBold needs no master — STAT axis values label locations in the continuous variable design space, and 600 is already interpolated and exposed as an fvar named instance; the STAT block simply lacked the matching label.
• Normalized master naming by dropping the "Normal" prefix to follow GF naming guidance.
• Added a fontspector check script and README section so the GF-profile QA can be run on demand against the variable font (or any named font file).

[github-actions]

Visit the preview URL for this PR (updated for commit 31acfc2):

https://grotesk-comparison-stand--pr-10-twgr1eth.web.app

_{(expires Sun, 27 Sep 2026 22:19:18 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: 79b50decca688a9a18871c69fe0ecb3e872353de}