refactor(remix): generate Fortal wrappers

[leoafarias]

Description

Replace the 25 historical handwritten Fortal* wrappers with deterministic
@MixWidget output while preserving the public APIs and behavior present on
main.

The annotations use explicit Remix widget targets and curated recipe
parameters. Generated constructors expose existing variant/size controls and
the underlying content/behavior parameters, while omitting style,
styleSpec, and non-widget recipe controls.

This PR also adds a clean-generation check that deletes every committed
.g.dart artifact, regenerates from source, and verifies byte-for-byte output.

Related Issues

Uses the generator support merged in
conceptadev/mix#997 and released
as mix_annotations 2.2.0-beta.1 and mix_generator 2.2.0-beta.2.

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Checklist

• My PR includes unit or integration tests for all changed/updated/fixed
  behaviors.
• I have updated or added relevant documentation (doc comments with ///).
• I am prepared to follow up on review comments in a timely manner.

Breaking Change

Does this PR require users of the package to manually update their code?

• Yes, this is a breaking change.
• No, this is not a breaking change.

Validation

• dart run tool/check_generated.dart — clean regeneration reproduced all 23
  committed artifacts byte-for-byte.
• flutter analyze — no issues.
• flutter test --reporter=failures-only — 1,889 tests passed.
• git diff --check — passed.
• GitHub CI — analyzer and package test workflow passed against the published
  Mix prereleases.

[leoafarias]

Superseded by #80

This PR is being closed without merging because the final Fortal
generator/API decision was completed on #80 after this branch was created.
Nothing is being discarded: every commit in this branch is already an ancestor
of #80, and #80 now targets main directly.

This branch must not be used as the final API reference. It still contains the
earlier contract:

• 25 curated factoryParameters annotations;
• public fortal*Styler recipe names;
• generated output that predates the final all-recipe-parameters surface.

The canonical contract is recorded in #80:

• target-only @MixWidget(target: RemixX.new);
• public fortalXStyle recipes;
• named variant constructors plus the unnamed constructor/public variant for
  dynamic selection;
• all recipe parameters exposed, including supported highContrast controls
  and Avatar fallbackLength;
• no #998/#999 variant-registration machinery.

PRs #92 and #93 remain valid feature drafts, but their workspaces must fetch
the latest #80 head, replay only their handwritten feature source/tests onto
feat/fortal-polish, regenerate all .g.dart files, and retarget their PR base
to feat/fortal-polish.

The feat/fortal-generated-wrappers branch is intentionally retained until
those dependent workspaces have migrated. Closing this PR does not delete or
rewrite that branch.