chore(opencode): set primary agents to Terra default

[xnoto]

Summary

Moves the nine primary agents that used kimi-for-coding/k3 / high to openai/gpt-5.6-terra / default. Reduces the three existing Terra reviewer subagents from xhigh to high.

Bumps the immutable opencode-server chart from 0.1.72 to 0.1.73 because packaged files/agents/*.md content changed.

Fixes #
N/A — owner-directed agent assignment update.

Type of change

• Feature / enhancement
• Bug fix
• Documentation
• Infrastructure (OpenTofu root or module)
• GitOps desired state (manifests, kustomize, charts, SOPS/KSOPS secrets)
• Container image
• CI / reusable workflow
• Refactor / cleanup
• Breaking change

Validation

• Required pull-request checks pass — workflow run 34610016083: repository hygiene/Helm validation, changed-chart detection, and opencode-server packaging succeeded.
• Generated or centrally distributed files were regenerated by their owning automation, not hand-edited — ConfigMap inclusion is Helm .Files.Glob rendering; no generated sources were edited.
• Exact net scope independently inspected: 12 agent front-matter assignments plus the required chart version bump.
• OpenCode agent model/variant front matter supports separate model and variant fields; default selects the model's default variant when available.
• Pre-PR reviews: adversarial code review and infrastructure security review returned ADVANCE; release readiness returned READY. QA identified no CI semantic-assignment assertion; the exact header values and net diff were manually checked before this PR.

Impact and rollout

Producer: makeitworkcloud/charts opencode-server package 0.1.73 changes packaged agent configuration only.

After a separately confirmed merge, the main workflow automatically packages and publishes the immutable chart, then opens/updates makeitworkcloud/kustomize-cluster's version-pin PR for workloads/apps/opencode-app.yaml. Its required checks and auto-merge govern desired-state selection. Reconciliation, pod replacement, health, and representative OpenCode behavior remain separate, unverified stages.

Rollback: publish and select a new immutable chart version restoring the prior assignments; do not attempt to republish 0.1.73.

Safety and secrets

• Contains no plaintext secrets, decrypted SOPS values, state files, kubeconfigs, tokens, or private endpoints
• No local OpenTofu init/plan/apply/destroy/import/state operations were run or claimed — plans come from pull-request checks
• Breaking or irreversible effects are described above with rollback notes

AI-assisted change; reviewer scrutiny requested for model/variant selection and chart versioning.

[github-actions]

Chart CI passed

Repository hygiene and Helm validation passed. View the workflow run.