fix(mix): accept *ListMix on shadow styler methods so token refs work

[tilucasoli]

Summary

• BoxStyler().boxShadows(token.mix()) failed to compile because the shadow styler methods took List<BoxShadowMix> while BoxShadowToken.mix() returns a BoxShadowListMixRef (implements BoxShadowListMix, not the raw list type). The same gap blocked .shadows() on Box/Flex/StackBox stylers and TextStyler.shadows() with ShadowToken.
• Change the shadow styler-mixin signatures to take the matching *ListMix wrapper and route through Prop.mix(value) so token refs flow end-to-end. Regenerated the affected .g.dart factory files; updated mix_tailwinds/tw_parser.dart for parity.
• Breaking: literal-list callers wrap with BoxShadowListMix([...]) / ShadowListMix([...]). Logged under Unreleased in packages/mix/CHANGELOG.md.

Fixes #925.

What changed

File	Change
packages/mix/lib/src/style/mixins/shadow_style_mixin.dart	boxShadows(List<BoxShadowMix>) → boxShadows(BoxShadowListMix)
packages/mix/lib/src/style/mixins/decoration_style_mixin.dart	shadows(List<BoxShadowMix>) → shadows(BoxShadowListMix)
packages/mix/lib/src/style/mixins/text_style_mixin.dart	shadows(List<ShadowMix>) → shadows(ShadowListMix)
packages/mix/lib/src/specs/{box,flexbox,stackbox,text}/*.g.dart	Regenerated BoxStyler.shadows / FlexBoxStyler.shadows / StackBoxStyler.shadows / TextStyler.shadows factory signatures to match.
packages/mix_tailwinds/lib/src/tw_parser.dart	Wrap parsed shadow lists with BoxShadowListMix(...) / ShadowListMix(...) before forwarding to the styler.
packages/mix/test/...	Updated literal-list callsites in box/flexbox/stackbox/text styler tests.
packages/mix/test/src/theme/tokens/shadow_list_token_integration_test.dart	New tests covering token.mix() and *ListMix literal flows.
packages/mix/CHANGELOG.md	New "Unreleased" entry documenting the breaking change.

Note: IconStyler.shadows(List<ShadowMix>) is intentionally unchanged — that setter is derived from the IconSpec.shadows field, not from TextStyleMixin. It can be migrated in a follow-up if we want IconStyler to accept ShadowToken.mix() too.

Migration

// Before
BoxStyler().boxShadows([
  BoxShadowMix(color: Colors.black, blurRadius: 8),
  BoxShadowMix(color: Colors.grey, blurRadius: 4),
]);

// After (literal)
BoxStyler().boxShadows(BoxShadowListMix([
  BoxShadowMix(color: Colors.black, blurRadius: 8),
  BoxShadowMix(color: Colors.grey, blurRadius: 4),
]));

// After (token — the case that motivated this fix)
const cardShadow = BoxShadowToken('shadows.card');
BoxStyler().boxShadows(cardShadow.mix());

The same wrapping applies to BoxStyler.shadows(...), FlexBoxStyler.shadows(...), StackBoxStyler.shadows(...), and TextStyler.shadows(...).

Test plan

• dart analyze . clean across all workspace packages (mix, mix_annotations, mix_generator, mix_lint, mix_tailwinds, mix_tailwinds_example).
• flutter test in packages/mix: 2726/2726 passing.
• flutter test in packages/mix_tailwinds: 322/322 passing.
• New integration tests in shadow_list_token_integration_test.dart:
  • BoxShadowToken.mix() returns a BoxShadowListMixRef that satisfies the BoxShadowListMix interface.
  • BoxStyler().boxShadows(token.mix()) compiles and produces a styler with the token-backed shadow prop.
  • BoxStyler().shadows(token.mix()) (the DecorationStyleMixin path) compiles and produces a styler.
  • BoxStyler().shadows(BoxShadowListMix([...])) literal form works.
  • End-to-end MixScope resolve: boxShadowToken.mix() resolves to the configured List<BoxShadow> at render time.
  • TextStyler().shadows(shadowToken.mix()) and the ShadowListMix([...]) literal form for text shadows.

DCM was skipped locally (not installed in this environment). Should be re-checked by CI.

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[leoafarias]

One verified medium-risk issue found around token-backed shadow list merging.

[leoafarias]

This handles direct BoxShadowToken.mix() usage, but it does not preserve the existing BoxShadowListMix merge semantics when the token-backed list is merged with a later literal list.

I verified this with a focused failing widget test:

final styler = BoxStyler()
    .boxShadows(token.mix()) // token resolves to BoxShadow(color: blue, blurRadius: 4)
    .boxShadows(BoxShadowListMix([BoxShadowMix(color: Colors.red)]));

The resolved shadow keeps the later red color, but blurRadius becomes 0.0 instead of preserving the token value 4. During resolution, Prop also logs that it cannot convert List<BoxShadow> to Mix<List<BoxShadow>>, so the token-resolved concrete list is skipped when Mix values are merged. The same issue reproduces for TextStyler.shadows with ShadowToken / List<Shadow>.

Existing shadow-list tests already establish index-wise in-place merge behavior for literal lists, so token-backed list sources should keep that behavior too. Please add conversion/normalization for List<BoxShadow> and List<Shadow> into BoxShadowListMix / ShadowListMix during mixed-source resolution, and add regression tests for token + literal list merges.