Align environment variables and update repository metadata

[francescobianco]

This pull request introduces several improvements to project documentation, configuration, and automation. The most significant changes include a major update to the README.md for better clarity and branding, the addition of CI workflows for code quality, and a shift in default server configuration to use http://localhost:8080 instead of a production URL. Documentation and sample configs have also been updated for consistency, and a new image asset and description sheet have been added for repository branding.

Documentation and Branding Updates

• Overhauled README.md: Improved structure, added badges, branding, and clarified usage instructions. Updated environment variable documentation and removed the local launcher script section. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
• Added a repository header image (repo-header-a4.png) and its description sheet for use in documentation and README.

Continuous Integration and Code Quality

• Introduced GitHub Actions workflows for automated linting and testing: added build.yml for multi-version Python lint/test and pylint.yml for static analysis. [1] [2]

Configuration and Environment Defaults

• Changed the default MCP_BASE_URL from https://mcp.openapi.com to http://localhost:8080 across documentation and example configs for safer local development and testing. [1] [2] [3] [4] [5]

Sample Configs and Usage Examples

• Updated all sample configuration files and code snippets to use the new default server URL and removed /mcp/ path suffixes for consistency. [1] [2] [3] [4] [5]

Minor Consistency and Terminology Fixes

• Standardized naming from "OpenAPI" to "Openapi" throughout documentation and scripts for consistency. [1] [2]