feat(dart/a2ui_core): complete v1.0 conformance, module layout, and 0.3.0 release - #3192

…r-basic-catalog

Brings in #3223 (the merged renames and LICENSE fix) and #3192
(a2ui_core 0.3.0). The README conflict is the basic catalog's Material
note next to lines #3223 left unchanged. Keep the note.

⚠️ Agent-generated

…bspec

The package now depends on a2ui_core ^0.3.0 (#3192), but the install
sample still showed ^0.2.2.

⚠️ Agent-generated

* feat(a2ui_flutter): add the framework adapter core

A2uiSurface renders a SurfaceModel through a NodeResolver, and NodeView
renders each ComponentNode through its catalog entry, rebuilding when the
node's props change. ComponentImplementation pairs a component schema with
a widget builder, WidgetCatalog is a catalog of them, and ComponentProps
reads a node's resolved properties, bindings and actions. A component
that has not arrived shows a small progress indicator.

* feat(a2ui_core): expose the v0.9 basic catalog's API

BasicCatalog.v0_9Api() returns the published v0.9 basic catalog document
parsed with Catalog.fromJson: its components, function signatures and theme
schema, so a framework adapter can read the component schemas without
embedding its own copy of the document.

* feat(a2ui_flutter): add the v0.9 basic catalog

package:a2ui_flutter/basic_catalog.dart implements the 18 components of the
v0.9 basic catalog with Material widgets, with their schemas from
a2ui_core's BasicCatalog.v0_9Api() and the functions of
BasicCatalog.v0_9(). basicCatalog() builds the whole catalog under the
basic catalog's id; BasicComponents holds each component for a catalog of
the app's own. The components apply the surface theme's primaryColor as
the primary color, and every specification example renders in a test.

* fix(a2ui_flutter): key a node's subtree by its implementation

A component whose catalogId changes is recreated with the same instance
id, like one whose type changes. Keying the subtree by the type name kept
the old implementation's state when only the catalog changed. Keying by
the resolved implementation resets it in both cases.

* test(a2ui_flutter): cover A2uiSurface.of and maybeOf

* fix(a2ui_flutter): forward the basic catalog's protocol version and instructions

* refactor(a2ui_flutter): rename WidgetCatalog to CatalogImplementation

Pairs it with CatalogApi in a2ui_core, as ComponentImplementation and
FunctionImplementation pair with ComponentApi and FunctionApi.

🤖 Agent-generated

* refactor(a2ui_flutter): use CatalogImplementation in the basic catalog

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* feat(a2ui_flutter): apply a component's accessibility label and description

NodeView wraps every resolved component in a Semantics that carries the
component's accessibility label as its label and its description as its
hint, so basic and custom components both get them. Without either
attribute the Semantics adds no node, and it stays in the tree so that
adding one later keeps the component's state.

🤖 Agent-generated

* fix(a2ui_flutter): adopt a2ui_core's renderer renames

#3194 renamed A2uiClientAction and A2uiClientError to A2uiRendererAction
and A2uiRendererError, MessageProcessor.groupModel to model and
getClientDataModel to getRendererDataModel, and replaced
EventSource.addListener with subscribe. The adapter's tests and README
still used the old names, so the package's tests no longer compiled on
main.

⚠️ Agent-generated

* fix(a2ui_flutter): use the http Apache license URL

#3205 standardized LICENSE files on http://www.apache.org/licenses/ and
made the license check enforce it. a2ui_flutter's LICENSE, added in
#3084, used https, so the static-checks job fails on main.

⚠️ Agent-generated

* docs(a2ui_flutter): match the README's a2ui_core constraint to the pubspec

The package now depends on a2ui_core ^0.3.0 (#3192), but the install
sample still showed ^0.2.2.

⚠️ Agent-generated

* docs(a2ui_flutter): drop accessibility from the README's unsupported list

NodeView applies a component's accessibility label and description, the
two attributes v0.9 defines, since effca52.

⚠️ Agent-generated

Prepares the first publish of a2ui_core since 0.2.2 and of a2ui_agent
since 0.0.1-wip004. Neither 0.3.0 nor 0.0.1-wip005 reached pub.dev when
their pubspecs were bumped (a2ui-project#3192, a2ui-project#2890), so this folds each package's
`## Unreleased` section into that version's section instead of opening a
third one.

While folding, the entries were checked against lib/ and corrected:

- a2ui_core: `PayloadValidator.protocolVersion`, `commonTypesSchema`,
  `checkVersion`, `forVersion` and `MessageProcessor.commonTypesSchema`
  were described as removed but still exist. `DataContext.isV10`,
  `A2uiCompileError`, `Catalog.protocolVersion` as a `String?` and the
  flattened `ComponentApi.schema` were never in a published version, so
  they are described in their final form rather than as renames or
  removals. `DataContext.dispose` does not exist. The new `intl` and
  `logging` dependencies are listed. Notes about tests and tooling are
  dropped and overlong lines are wrapped.
- a2ui_agent: payload checks go through `MessageProcessor.forAgent`, not
  `Catalog.withFunctions`. Entries that revised unpublished wip005
  entries are merged into them, including the v1.0 entries from a2ui-project#3242.

No code changes. The versions in pubspec.yaml were already set.

## Why

`a2ui_core` is `0.3.0` on `main`, but pub.dev still has `0.2.2`: the version bump in #3192 was never followed by a publish, and later PRs stacked a new `## Unreleased` section on top. This PR is the release PR described in [docs/contributing/release.md](https://github.com/a2ui-project/a2ui/blob/main/docs/contributing/release.md#pubdev-publishing-steps): it folds `## Unreleased` into `## 0.3.0`, the version that will actually ship, so the changelog has one section per published version.

Relative to the published 0.2.2, 0.3.0 is a minor bump that covers the breaking renames (`A2uiClientAction` to `A2uiRendererAction`, `EventListenable.addListener` to `EventSource.subscribe`, `MessageProcessor.groupModel` to `model`, `DataPath` and `MinimalCatalog` removed, and so on).

`a2ui_agent` is not part of this release: its `-wip` versions are published only by exception, when someone needs to try the package outside the repo, so its changelog is left as it is on `main`.

## What changed

While folding, each entry was checked against `lib/`, and the ones that did not match were corrected:

- `PayloadValidator.protocolVersion`, `commonTypesSchema`, `checkVersion`, `PayloadValidator.forVersion`, `MessageProcessor.commonTypesSchema` and the `version` parameter of `validatorFor` were described as removed. They all still exist; the entry now lists only `A2uiValidationError.details` and `MinimalCatalog` as removed, and mentions `PayloadValidator.commonTypesFor`.
- `DataContext.isV10`, `A2uiCompileError`, `Catalog.protocolVersion` as a `String?`, `ComponentNode.props` before `ResolvedBinding`, and the flattened `ComponentApi.schema` were never in a published version. They are described once, in their final form, instead of as renames, removals or breaking changes; two entries that contradicted each other (`isV10` to `usesDirectives` vs. `atLeastV10`; `allOf` flattened vs. kept as written; `dispatchAction` emitting only `event` vs. `event` and `name`) are resolved in favor of what the code does.
- `DataContext.dispose` does not exist and is no longer mentioned; `resolveListenableWithPending` was not in 0.2.2, so `resolveSignalWithPending` is listed as added.
- The new `package:intl` and `package:logging` dependencies get an entry.
- Three duplicate additions of `Catalog.protocolVersion` are merged into one.
- Notes about tests, conformance runners, a private `_subscribe` helper and `tool/generate_basic_catalogs.dart` are dropped, and single-line bullets of up to 1689 characters are wrapped.

No code changes. The version in `pubspec.yaml` was already set.

## Testing

- `dart pub publish --dry-run` in `dart/a2ui_core`: 0 warnings.
- `yarn dlx [email protected] --config .prettierrc --check dart/a2ui_core/CHANGELOG.md` passes.
- Every symbol named in the corrected entries was located in `dart/a2ui_core/lib`.