* chore: add PR template, issue templates, and contribution policy
Drive-by feature PRs are becoming a problem. This adds guardrails:
- PR template with type selection, checklist, and AI disclosure
- Bug report issue template (structured YAML form)
- Issue config that redirects features to Discussions and disables blank issues
- PR compliance workflow that enforces template completion and requires
a Discussion link for feature PRs
- Contribution policy in CONTRIBUTING.md (acceptance tiers, AI PR rules)
- Agent-facing rules in AGENTS.md (follow the template, no bulk changes)
* fornat
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