ci: add vglyph checks

[GGRei]

Summary

This adds a CI workflow for vglyph on Linux, macOS, and Windows.

The workflow installs the native rendering dependencies, verifies the required pkg-config modules, runs the vglyph tests, and compiles the examples without launching GUI windows.

Linux also runs formatting and markdown checks.

Changes

• Add CI Checks / Linux, CI Checks / macOS, and CI Checks / Windows jobs.
• Install V from the current upstream compiler.
• Install native dependencies for FreeType, HarfBuzz, FriBidi, Fontconfig, Pango, GLib/GObject.
• Run root vglyph tests only, avoiding accidental recursive testing of downloaded toolchains.
• Compile tracked direct examples from examples/*.v.
• Mount the checkout as a temporary VMODULES/vglyph module so examples and docs use the PR code.
• Add readable test/example counters in CI logs.

Tests

v run _check.vsh
git diff --check