[4/5] OpenAPI operation routing for workflows

[odyslam]

Supersedes the closed oversized PR #90.

Review order

1. [1/5] Human CLI output and agent contract guards #96: Human CLI output and agent contract guards
2. [2/5] API command and workflow output foundation #98: API command and workflow output foundation
3. [3/5] Workflow contract and module architecture #100: Workflow contract and module architecture
4. [4/5] OpenAPI operation routing for workflows #101: OpenAPI operation routing for workflows ← this PR
5. [5/5] Generated-client pruning and stale API cleanup #102: Generated-client pruning and stale API surface cleanup

Base / head

Base: codex/pcl-workflow-module-split
Head: codex/pcl-openapi-operation-routing

What changed

• Routes workflow API interactions through generated OpenAPI operations.
• Removes the old manual workflow request constructors.
• Keeps workflow definitions tied to operation IDs instead of hand-crafted request paths.

Review focus

• Any remaining hand-built API interaction paths in promoted workflows.
• OpenAPI operation mapping correctness for projects, releases, incidents, and outer workflow surfaces.
• Tests proving workflow commands still resolve to intended operations.

Validation

Validated on the final stack tip codex/pcl-slim-generated-client:

• make ci
• Local ./target/debug/pcl api manifest --toon shows operation IDs for promoted workflows.