Implement comprehensive CI/CD pipeline with best practices

Major improvements:
- Matrix testing across Linux (stable/beta/nightly), Windows, and macOS
- Test with multiple feature combinations (default, yara-scanning, no-default)
- Code coverage reporting with codecov integration
- Security auditing with cargo-audit and dependency review
- Automated release builds for multiple targets
- Performance benchmarking with trend tracking
- Concurrency control to cancel outdated runs
- Rust cache optimization for faster builds
- Documentation generation checks
- Weekly scheduled runs for proactive monitoring

Additional workflows:
- Automated dependency updates via Dependabot
- Weekly Cargo dependency update PRs
- Stale issue and PR management

Project templates:
- Pull request template with checklist
- Bug report issue template
- Feature request issue template
- Codecov configuration with 70% coverage target

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,36 @@
+---
+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.