Issue and PR templates, and a create-ticket skill

[bracyw]

Changes

Delphi gets Argos's issue templates (idea, spike, epic, dev work) and a PR template. A short root .claude/skills/create-ticket points to the shared create-ticket rules and adds only Delphi's specifics.

Notes

• Ideas and spikes carry no issue type, matching the shared create-ticket rules. Delphi has no area labels.
• The category and written-by labels get created when the first ticket is filed.