Prepare redline 0.3.0 release

[gowtham0992]

What changed

• Prepare redline 0.3.0 release metadata.
• Add 0.3.0 changelog covering guided app, quick-check, status, auto import, suite readiness, richer reports, MCP expansion, and product proof.
• Align README, release docs, GitHub Action examples, PyPI metadata, and MCP registry metadata with 0.3.0.

Validation

• python -m pytest -q
• python -m ruff check .
• python -m mypy redline tests scripts examples
• git diff --check
• bash scripts/action_smoke.sh /tmp/redline-action-smoke-v0.3.0-prep
• bash scripts/build_release.sh /tmp/redline-dist-v0.3.0-prep