Configure model settings for commands, agents, and skills

Set explicit model preferences to optimize for speed vs capability:

- haiku: 11 commands, 2 agents (issue-worker, pr-fixer), 10 skills
  Fast execution for straightforward tasks

- sonnet: 4 commands (groom, improve, plan-issues, review-pr),
  1 agent (code-reviewer)
  Better judgment for analysis and review tasks

- opus: 2 commands (arch-refine-issue, arch-review-repo),
  1 agent (software-architect)
  Deep reasoning for architectural analysis

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

skills/backlog-grooming/SKILL.md

@@ -1,5 +1,6 @@
 ---
 name: backlog-grooming
+model: haiku
 description: Review and improve existing issues for clarity and actionability. Use when grooming the backlog, reviewing issue quality, cleaning up stale issues, or when the user wants to improve existing issues.
 user-invocable: false
 ---