Add complexity indicator to issue body template

[sebastientaggart]

Add a "Complexity" section to the /start issue body template with a self-evident "Verification / QA effort" scale (trivial / moderate / significant / extensive) and a one-line justification.

This gives PMs and BAs an at-a-glance sense of how much human verification effort a ticket requires, without needing a legend or point system.

Issue #91

[sebastientaggart]

Review Summary

Verdict: APPROVE

Findings

No issues found. Code looks correct and follows project conventions.

The PR adds a "Complexity" section to the /start issue body template across the canonical source (skills/start.md) and all four adapter copies (Claude, Codex, Cursor, Gemini). The section count was correctly updated from "four" to "five", the complexity scale guidance is clearly scoped as agent-internal, and the sync hashes were regenerated. All five files carry identical content changes.