[owjs3901]

Summary

NEW-04: token names were checked for clashes only within one kind (check_token_names / flatten_color_value). A color card and a shadow card therefore both declared --card, and whichever came last in :root silently replaced the other.

• Theme now uses serde's remote = "Self" pattern. The derived field-by-field deserialization stays as it was, and the trait Deserialize impl then runs check_token_kinds over the whole theme. Every path that reads a theme gets the check: the wasm and napi registerTheme decode, and serde_json.
• check_token_kinds compares the CSS variables of colors (every variant, css_key), length and shadow (css_key_from, so gray.100 and gray-100 are the same variable). The same name in two variants of one kind is still allowed, because it is the same variable on purpose.
• The atom identity fixture first_value.rs gave a length and a shadow the same name space, which is exactly this clash. The shadow is now called lift. The assertions still check that a shadow token's first value resolves on its own.
• Docs: the colors page notes that colors, length and shadow share one namespace.

New build error:

• theme: color token 'card' and shadow token 'card' both become the CSS variable --card: rename one

Refs #685

Test plan

• cargo test -p sheet --lib (234 passed)
• cargo clippy -p sheet --all-targets -- -D warnings, cargo fmt --all -- --check
• apps/landing/devup.json checked for cross-kind clashes (none)
• CI: full test suite + tarpaulin 100%

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
libs/sheet/src/theme.rs	100.00% <100.00%> (ø)

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