Clean up documentation and remove unnecessary files

- Rewrote CONTRIBUTING.md in casual, direct style
- Rewrote SECURITY.md to be less formal
- Fixed GitHub URLs in CHANGELOG.md
- Removed formal issue/PR templates
- Removed codecov.yml configuration file

All docs now sound human, not AI-generated.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,44 +0,0 @@
----
-name: Bug Report
-about: Create a report to help us improve
-title: '[BUG] '
-labels: bug
-assignees: ''
----
-
-## Bug Description
-
-A clear and concise description of what the bug is.
-
-## To Reproduce
-
-Steps to reproduce the behavior:
-1. Run '...'
-2. Execute '...'
-3. See error
-
-## Expected Behavior
-
-A clear and concise description of what you expected to happen.
-
-## Actual Behavior
-
-What actually happened.
-
-## Environment
-
-- OS: [e.g., Windows 11, Ubuntu 22.04, macOS 14]
-- Ghost Version: [e.g., 0.1.0]
-- Rust Version: [e.g., 1.75.0]
-
-## Additional Context
-
-Add any other context about the problem here, including:
-- Log output
-- Stack traces
-- Configuration files
-- Screenshots (if applicable)
-
-## Possible Solution
-
-If you have ideas on how to fix the bug, please share them here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,36 +0,0 @@
----
-name: Feature Request
-about: Suggest an idea for this project
-title: '[FEATURE] '
-labels: enhancement
-assignees: ''
----
-
-## Feature Description
-
-A clear and concise description of what feature you'd like to see.
-
-## Problem Statement
-
-Is your feature request related to a problem? Please describe.
-Example: I'm always frustrated when [...]
-
-## Proposed Solution
-
-A clear and concise description of what you want to happen.
-
-## Alternatives Considered
-
-A clear and concise description of any alternative solutions or features you've considered.
-
-## Use Case
-
-Describe the use case or scenario where this feature would be useful.
-
-## Implementation Ideas
-
-If you have thoughts on how this could be implemented, please share them here.
-
-## Additional Context
-
-Add any other context, screenshots, or examples about the feature request here.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,37 +0,0 @@
-## Description
-
-Please provide a clear and concise description of what this PR does.
-
-## 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
-- [ ] Performance improvement
-- [ ] Code refactoring
-- [ ] Test improvements
-
-## How Has This Been Tested?
-
-Please describe the tests that you ran to verify your changes.
-
-- [ ] Unit tests
-- [ ] Integration tests
-- [ ] Manual testing
-- [ ] Platform-specific testing (Windows/Linux/macOS)
-
-## Checklist
-
-- [ ] My code follows the project's style guidelines
-- [ ] I have performed a self-review of my own code
-- [ ] I have commented my code, particularly in hard-to-understand areas
-- [ ] I have made corresponding changes to the documentation
-- [ ] My changes generate no new warnings
-- [ ] I have added tests that prove my fix is effective or that my feature works
-- [ ] New and existing unit tests pass locally with my changes
-- [ ] Any dependent changes have been merged and published
-
-## Additional Context
-
-Add any other context about the pull request here.