chore: upgrade to Flutter 3.29

[matthiasn]

From Copilot:
This pull request includes several updates to dependencies, configuration files, and project settings. The most important changes include updating the Flutter SDK version, modifying project settings for iOS and macOS, and updating dependencies in the pubspec.yaml file.

Dependency Updates:

• Updated Flutter SDK version from 3.27.4 to 3.29.0 in .fvm/flutter_sdk, .fvm/fvm_config.json, and .fvmrc files. [1] [2] [3]
• Updated flutter_map dependency from ^7.0.0 to ^8.0.0 in pubspec.yaml.
• Changed gpt_markdown dependency to use a specific git reference instead of a version in pubspec.yaml.
• Updated analyzer and dart_style dependencies in pubspec.yaml under dev_dependencies.

Project Settings:

• Enabled GPU validation mode for iOS and macOS in Runner.xcscheme files. [1] [2]

Version Update:

• Incremented project version in pubspec.yaml from 0.9.568+2884 to 0.9.569+2885.