chore: rebrand project to openGecko and update logo

[ZhengZhenyu]

• Rename project from OmniContent to openGecko across all files
• Update database names: omnicontent.db -> opengecko.db
• Add new openGecko logo and integrate in frontend
• Fix login page logo styling to prevent distortion
• Update GitHub URLs to opensourceways/openGecko
• Update Docker image names to opengecko-*
• Update all documentation with new project name
• Maintain proper logo aspect ratio and centering

Description

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📝 Documentation update
• 🔧 Configuration change
• 🎨 Code refactoring (no functional changes)
• ⚡️ Performance improvement
• ✅ Test addition or update

Related Issues

Closes #
Related to #

Changes Made

Database Changes

• No database changes
• New tables added
• Existing tables modified
• Migration script included: alembic/versions/XXXXX_*.py
• Migration tested locally
• Rollback tested

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing completed
• Test script provided

Test Instructions

# How to test these changes

Screenshots (if applicable)

Checklist

Code Quality

• Code follows project style guidelines
• Self-review completed
• Comments added for complex logic
• No console.log or debug statements left
• No commented-out code left

Functionality

• All tests pass locally
• No breaking changes (or documented if necessary)
• Error handling implemented
• Edge cases considered

Security

• No sensitive data in code
• Input validation added
• Authentication/authorization checked
• Dependencies are up to date

Documentation

• Code is self-documenting or commented
• API documentation updated (if applicable)
• README updated (if applicable)
• Migration guide provided (if applicable)

Deployment Notes

• No special deployment steps needed
• Database migration required
• Environment variables need update
• Configuration files need update

Migration Instructions

# Step-by-step migration instructions
cd backend
alembic upgrade head

Performance Impact

• No performance impact
• Improves performance
• May impact performance (details below)

Backward Compatibility

• Fully backward compatible
• Requires manual migration
• Breaking changes (migration guide included)

Additional Notes

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AI Assistance Declaration

• AI assistance used (Claude, GitHub Copilot, etc.)
• All AI-generated code reviewed and tested
• Co-authored-by tag included in commit

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🤖 This PR follows the contribution guidelines

[opensourceways-bot]

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