V0.2 Enhance playlist management, search functionality, and release gates

[TrVHau]

This pull request introduces a comprehensive release readiness and quality gate workflow for the project, along with related documentation, configuration, and codebase updates. It adds scripts and CI automation for enforcing release policies, artifact integrity, documentation synchronization, and quality thresholds. Additionally, it updates the application logic to support watcher-driven rescans and improves the release and install documentation.

Release and Quality Automation

• Added a GitHub Actions workflow (.github/workflows/release-gate.yml) to automate release readiness checks, artifact publishing validation, and artifact upload steps.
• Introduced scripts for quality and release gates: scripts/quality-gate.sh (runs tests and lints), scripts/release-gate.sh (enforces release policy, docs sync, integrity, and logs approvals), and scripts/publish-check.sh (validates package publishability). [1] [2] [3]
• Added configuration files: config/release-policy.toml (release policy), config/quality-thresholds.toml (quality metrics), and config/docs-sync-checklist.md (docs sync policy). [1] [2] [3]

Documentation and Contribution Process

• Updated README.md with install instructions, build prerequisites, new directory structure, and detailed sections for quality and release gates, including their inputs and outputs. [1] [2] [3]
• Enhanced CONTRIBUTING.md to reference the new release and docs impact checks, and to align contribution steps with the new scripts. [1] [2]
• Added a new pull request template (.github/PULL_REQUEST_TEMPLATE.md) requiring summary, testing, docs impact, and release readiness checklists.

Application Logic Improvements

• Updated the application boot and scan logic in src/app/actions/boot.rs to support watcher-driven rescans, batching, and improved scan state management, including tracking scan generations and handling warnings. [1] [2] [3] [4] [5] [6]
• Added module imports for new features in src/app/actions/mod.rs.

Packaging and Metadata

• Bumped crate version to 0.2.0 and explicitly defined the binary target in Cargo.toml. [1] [2]

These changes collectively establish a robust, automated release process with enforced quality and documentation standards, while improving developer experience and reliability for end users.