Prepare public source release

[hkimw]

Summary:

• Add public quickstart, smoke entry point, release guide, and v2026.5.24 release notes.
• Document install, usage, release, contribution, and local validation boundaries in the README.
• Keep private-path filtering generic while preserving local source/privacy guards.

Validation:

• bash scripts/smoke.sh
• bash scripts/vscode-adapter-smoke.sh
• git diff --check
• public visibility verified: pccxai/systemverilog-ide is PUBLIC