feat(remix): add textarea component

[leoafarias]

Description

Adds RemixTextArea as a constructor-only multiline facade over RemixTextField. It shares the same TextFieldSpec, TextFieldStyler, NakedTextField, controller, focus, editing, selection, and semantics implementation—there is no second editable pipeline or TextArea-specific generated style machinery.

Component API

RemixTextArea supplies safe multiline defaults:

• minLines: 2
• maxLines: null
• keyboardType: TextInputType.multiline
• textInputAction: TextInputAction.newline
• expands: false
• obscureText: false

It forwards the supported TextField controller, focus, editing, selection, scrolling, restoration, IME, accessory, semantics, style, and raw style-spec surface.

Shared TextField corrections

• Multiline hints align to directional top-start while single-line hints remain centered.
• Label, hint, helper, and error semantics are announced once.
• Interactive leading/trailing accessories remain separate semantic nodes.
• Whole-control fallback taps preserve focus and press behavior without duplicating semantic actions.
• Editable selection and scrolling remain owned by NakedTextField.
• Input-row CrossAxisAlignment.baseline uses Flutter's alphabetic baseline and renders real text/accessories without the prior Row assertion.

Mix/code-generation surface

• container is now StyleSpec<BoxSpec> and accepts BoxStyler, matching the actual outer renderer.
• Input-row spacing and crossAxisAlignment are generated top-level fields.
• The outer label/input/helper layout remains StyleSpec<FlexBoxSpec>.
• No handwritten generated-style forwarding extension was added.
• Clean generation reproduced all 25 committed artifacts byte-for-byte.

Migration example:

// Before
TextFieldStyler().container(
  FlexBoxStyler()
    .spacing(8)
    .crossAxisAlignment(CrossAxisAlignment.center),
);

// After
TextFieldStyler()
    .container(BoxStyler())
    .spacing(8)
    .crossAxisAlignment(CrossAxisAlignment.center);

Visual Evidence

Captured and visually verified locally; the PNGs are ignored and are not part of the package diff:

• .context/screenshots/textarea-light.png — 368×796, SHA-256 fed0cd66eb4e9d01fe79dcf829c5997a26ed467055d3502b49ff222e94c97eec
• .context/screenshots/textarea-dark.png — 368×796, SHA-256 e2edf10274afa5b07bb220de9d83bd15e4a2b34ca5c3f3d2d41b6078f65ddee0

The captures include focused empty, filled multiline, error, disabled, read-only, and custom-styled states. Hosted GitHub attachment upload remains pending because the connector and CLI do not expose the issue-attachment endpoint.

Validation

• fvm flutter test packages/remix/test/components/textfield packages/remix/test/public_api_test.dart packages/remix/test/public_api_compatibility_test.dart — 170/170 passed on hosted naked_ui 1.0.0-beta.9, including multiline scrolling, selection-drag, and rapid double-tap pressed-state regressions.
• fvm dart run melos run generate:check — 25 generated artifacts reproduced byte-for-byte.
• fvm flutter analyze --fatal-infos — clean.
• Fortal parity verified the hosted naked_ui 1.0.0-beta.9 resolution while retaining the compatible ^1.0.0-beta.8 package constraint.
• GitHub test / Run tests for all packages on final head d1a06e269 — passed.
• Formatting, conflict-marker scan, and git diff --check — clean.

naked_ui 1.0.0-beta.9 contains the pressed-state lifecycle fix from conceptadev/naked_ui#84, and this branch's lockfile now resolves that hosted release.

Related Issues

• Resolved upstream by fix(naked-ui): correct selection semantics and press state naked_ui#84 and released in naked_ui 1.0.0-beta.9.

---

Draft gates

• TextArea API/forwarding review complete.
• Shared semantics/gesture review complete.
• Mix code-generation and baseline render review complete.
• Local light/dark screenshots captured, retained, and visually inspected.
• Naked UI refactor(remix): generate Fortal wrappers #84 is merged and released in a compatible prerelease.
• Remix lock resolves that release and all TextField/TextArea tests pass.
• Full repository CI passes on the final dependency resolution.
• Hosted screenshots are attached to this PR.
• Manual VoiceOver/TalkBack, web accessibility-tree, keyboard/selection, RTL, narrow-width, and 200% text-scale checks are recorded.

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.

Consumers styling TextField input-row layout through container(FlexBoxStyler(...)) must migrate container visuals to BoxStyler and use the generated top-level spacing and crossAxisAlignment methods.