[Chore] add issue forms for Epic and Task workflow

[learncold]

Summary

• add GitHub issue forms for Epic and Task creation
• disable blank issues so new work uses the repository workflow
• document issue creation rules in CONTRIBUTING.md

Related Issue

• Closes Chore: add issue forms for Epic and Task workflow #38

Area

• Engine
• Domain
• Application
• Docs
• Build
• Analysis
• Chore

Architecture Check

• I kept the dependency direction application -> domain -> engine.
• I did not add Qt UI code to src/domain.
• I did not add domain or application dependencies to src/engine.
• I used src/ as the include root.

Verification

• cmake --preset windows-debug
• cmake --build --preset build-debug
• Not run (reason below)
• Verification focused on GitHub repository configuration files only.
• No local build behavior changed in this PR.

Risks / Follow-up

• Existing issue titles are not retroactively normalized by this change; the forms guide future issues.
• Once the codebase becomes active, you may want to add additional issue forms for bugs or release work if the workflow expands.