Require agents to follow issue title guidance - #683

Why

Issue titles are primary navigation for open work, but agents had no shared contract for naming outcomes, distinguishing product surfaces, or separating title content from labels and issue bodies.

What changes

Before:

Agents relied on local judgment when creating issues or changing Story and Quest titles.

After:

Agents must read and follow one issue-title guide before creating an issue or changing a Story or Quest title. The guide also defines the refinement interview used for corpus reviews.

Review guide

Start with: .agents/issue-titles.md

Then review:

1. The outcome, terminology, metadata, and status rules
2. The completion and overlap audit
3. The repository-wide instruction in AGENTS.md

How to verify it

• git diff --check verifies the documentation changes contain no whitespace errors.
• Read the issue-title instruction in AGENTS.md and confirm it applies to one-off issue creation as well as corpus reviews.

Scope

Included

• Issue-title and metadata rules derived from the completed open-issue review
• A repeatable refinement interview for reviewing a set of titles
• A repository-wide requirement that agents use the guide when creating issues

Intentionally unchanged

• Existing issue bodies and titles, which were updated during the completed review
• Executable enforcement or GitHub automation

Scope confirmation

• Every changed file supports the purpose described above.
• Unrelated cleanup and formatting changes are excluded.
• Generated or mechanical changes are clearly identified.
• The description matches the final diff and test results.