Added flutter/dart support

[majmohar4]

Add Dart / Flutter support

Adds a Dart analyzer so CodeWiki can document Dart and Flutter projects. .dart files go through the same dependency-analysis and doc-generation pipeline as the other languages.

What's included

Core Dart analysis (analyzers/dart.py, analyzers/dart_imports.py)

• Classes, mixins, extensions, enums, top-level functions/getters and methods become components.
• Edges for inheritance (extends / with / implements), field types, instantiations and calls.
• package: and relative imports, exports and part/part of files decide which definition a name resolves to.
• Library-private (_name) declarations never resolve outside their library.
• Names not visible through imports are dropped instead of guessed, so there are no cross-language false matches (e.g. Row resolving to a Kotlin class).
• Extension method calls are routed through the extension's on type, and this.field receivers are resolved.

Flutter-aware edges (analyzers/dart_flutter.py)

• Widgets and State classes are typed, and instantiations inside build() become widget-to-widget edges.
• ref.watch / ref.read link widgets to Riverpod providers, including @riverpod codegen.
• GoRouter routes link to their screen widgets.
• Dart modules get Flutter-specific documentation hints in the prompt.

Robustness

• Generated files (*.g.dart, *.freezed.dart, etc.) and .dart_tool/ are ignored.
• Dart 3.8 null-aware collection elements (?x) are blanked before parsing, because the bundled grammar doesn't support them yet. Byte positions are unchanged.

Other changes

• tree-sitter-language-pack is pinned to >=0.8.0,<0.9.0. The Dart grammar/API in 0.9 is not yet verified.
• README, CHANGELOG and guides/development.md are updated.
• .dart is added to the CLI/MCP language validation.

Testing

• New tests: tests/test_dart_analyzer.py, tests/test_dart_flutter.py, tests/test_dart_imports.py, tests/test_doc_layout.py. All 62 pass.
• Tried on real Flutter apps using Riverpod and GoRouter.

Notes for reviewers

• Only call_graph_analyzer.py changes in a significant way (+156 lines) ou, to register the analyzer and the Dart file handling.

[anhnh2002]

Thanks a lot for this, @majmohar4. I pushed three small commits on top of your branch (hope that's OK):

1. Exact names before short names in scoped resolution (3be8974). _dart_scope_candidates merged exact and short-name hits before requiring one unique match. So an imported top-level helper() became ambiguous whenever any visible class also had a helper method, and the edge was dropped. Exact names are now tried first, which also matches Dart's own lookup order.
2. Fallback when there's no pubspec.yaml (54e7d7b). If CodeWiki is run on e.g. myapp/lib, package: imports can't be mapped to files. Every caller was still treated as scoped, so almost all cross-file edges disappeared without any warning. In that case we now keep the library-private rules, match public names across Dart files only, and log a warning.
3. Dropped *.config.dart from the default ignores (9d8c538). It catches injectable's generated file, but hand-written app.config.dart-style files are common and were being skipped.

Left for follow-ups:

• show/hide combinators aren't applied yet, so a hidden name can still make a lookup ambiguous. That needs per-import name filters.
• For conditional imports, keeping only the default URI is the right call. Adding the platform variants would make every shared name ambiguous.
• Scope sets are stored per file, so memory grows roughly with files² in very large apps with barrel files. Sharing them per import set would fix it.