Add Definition of Done document

[replakcan]

Description

Create a Definition of Done document for tasks and pull requests.

Scope

• Define when an issue is considered complete
• Define build requirements
• Define documentation requirements
• Define review requirements
• Define deployment expectations

Out of Scope

• Automated enforcement of all rules
• Branch protection setup

Acceptance Criteria

• docs/definition-of-done.md exists
• Build requirement is documented
• Static export compatibility requirement is documented
• Documentation update expectation is documented
• PR review expectation is documented
• Deployment success expectation is documented

Technical Notes

• Keep it simple and practical.

Related

• Related to: Create PR review guidelines document