Update README.md to accurately represent P Foundation before public launch

[Copilot]

The current README.md was outdated and still referenced the original fork's personal website content instead of accurately representing the P Foundation. This PR completely updates the README to provide comprehensive information about the foundation before its public launch.

Changes Made

• Replaced outdated content: Removed all references to the personal website and replaced with P Foundation information
• Added comprehensive foundation overview: Included mission statement, organizational structure, and 501(c)(3) status
• Documented core values: Added the four guiding principles (Patriotism, Passion, Persistence, Partnership)
• Included background & rationale: Explained the foundation's origins and the challenges that led to its creation
• Listed current programs: Detailed descriptions of MediaGuard, CitizenMesh, and ResilientNet programs
• Added future roadmap: Included strategic goals and plans through 2027
• Proper branding: Updated logo reference to use P Foundation's actual logo
• Preserved technical docs: Maintained all development setup instructions for contributors
• Added contact information: Included relevant email addresses and website links

Before/After

Before: Referenced "Paweł Kosiec - Personal Website" with outdated personal branding
After: Professional P Foundation README with comprehensive organizational information

The README now accurately represents the foundation's identity, mission, and programs, making it welcoming and informative for the public launch.

Fixes #75.

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