feat(flutter-cursor-templates): introduce MCP integration and conventions in project brief

- Added optional MCP integration settings in project-brief.yaml, allowing for environment-based server configurations.
- Introduced conventions for strict package imports to enhance code organization and maintainability.
- Updated brief schema to validate new MCP properties and ensure correct usage.
- Implemented MCP JSON builder to generate .cursor/mcp.json based on project brief settings.
- Enhanced resolver to include MCP configuration in generated files when enabled.

This update improves integration capabilities and enforces coding standards across the project.

flutter-cursor-templates/templates/rules/theming/theming.mdc.tmpl

@@ -0,0 +1,20 @@
+---
+description: Semantic colours and theme extensions for {{PROJECT_NAME}}
+globs: ["lib/**/*.dart", "test/**/*.dart"]
+alwaysApply: false
+---
+
+# Theming — {{PROJECT_NAME}}
+
+## Context
+Theme variants from brief: **{{THEME_SUMMARY}}**.{{HIGH_CONTRAST_NOTE}}
+
+## Constraints
+- Prefer **`ThemeExtension`** (or design-system equivalents) for app-specific colours and radii — avoid raw `Color(0xFF...)` in feature code except in central token definitions
+- Use **`Theme.of(context).colorScheme`** / `TextTheme` for Material-aligned roles where appropriate
+- **High contrast:** when supported, verify WCAG contrast for text and controls; never rely on colour alone for state (pair with icon or label){{HIGH_CONTRAST_UX_LINE}}
+- Touch targets: respect platform minimums (e.g. ~48 logical pixels) for interactive widgets
+
+## Anti-patterns
+- Hard-coded `Colors.*` scattered across feature widgets instead of theme tokens
+- Ignoring `MediaQuery.of(context).platformBrightness` / high-contrast modes when the product claims support