Use shared PR review workflows

[yurevichcv]

Summary

• Add three thin PR review workflow callers: OpenCode Kimi, OpenCode DeepSeek, and PR-Agent DeepSeek.
• Delegate agent logic to the shared workflows in segmentstream-agents.
• Pass only OPENROUTER_API_KEY to the shared workflows instead of inheriting all repository secrets.

Rollout note

The callers temporarily reference the shared workflow branch while the central PR is open:
https://github.com/segmentstream/segmentstream-agents/pull/31

Before merging rollout PRs, we should switch these refs to @main after the central PR lands.

Manual trigger

Comment /review on a pull request to trigger the agents manually.

Validation

• YAML parse check passed locally for all generated workflow files.
• git diff --check passed across the rollout branches.
• The shared-workflow path was retested in segmentstream-mcp:
  • OpenCode DeepSeek: https://github.com/segmentstream/segmentstream-mcp/actions/runs/25958339732
  • OpenCode Kimi: https://github.com/segmentstream/segmentstream-mcp/actions/runs/25958339758
  • PR-Agent DeepSeek: https://github.com/segmentstream/segmentstream-mcp/actions/runs/25958339744

[yurevichcv]

Closing this rollout PR for now. GeoLift is a public fork, so it cannot use private reusable workflows from segmentstream-agents without a different repository strategy.