feat: Update editorconfig to use tabs by default

[agraven-famedly]

Update the editorconfig so tabs are the default. The original choices of spaces was not well-motivated and tabs suit us better (we strive to use them everywhere we can for accessibility and flexibility reasons).

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Note

Low Risk
Editor and formatter hints only; no runtime or security impact, though editors may suggest tabs for file types that previously defaulted to spaces.

Overview
EditorConfig now treats tabs as the default for all files (indent_style / indent_size on [*]), replacing the previous default of 2 spaces.

Per-language rules are reorganized: explicit 2-space overrides are added for *.dart, *.nix, *.toml, and *.{yaml,yml}. The old tab-only sections for shell, Makefiles, Rust, and Go are removed because they inherit the new global default.

The same content is updated in standards/editorconfig (source) and .editorconfig (generated copy via filegen-activate).

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[RasmusRendal]

Looks cool!
Let's merge it tomorrow if nobody complains before then :)

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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