[5/5] Generated-client pruning and stale API cleanup

[odyslam]

Supersedes the closed oversized PR #90. This is intentionally last because it contains the generated-client churn.

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
5. [5/5] Generated-client pruning and stale API cleanup #102: Generated-client pruning and stale API surface cleanup ← this PR

Base / head

Base: codex/pcl-openapi-operation-routing
Head: codex/pcl-slim-generated-client

What changed

• Applies the previously stashed generated-client pruning in an isolated final PR.
• Adds a build-time OpenAPI spec transform so progenitor emits a smaller client surface.
• Removes stale/raw API aliases and stale workflow surface that no longer belongs in the product path.
• Keeps the large generated-client churn out of the behavior-focused PRs below it.

Review focus

• Review crates/dapp-api-client/build/spec_transform.rs and its tests before the generated file.
• Treat crates/dapp-api-client/src/generated/client.rs as generated output from the transform.
• Confirm removed stale API surfaces and command aliases are intentional.

Validation

Validated on this stack tip:

• make ci
• ./target/debug/pcl --toon --llms
• ./target/debug/pcl doctor --toon
• PCL_AUTH_NO_BROWSER=1 ./target/debug/pcl auth ensure --toon
• ./target/debug/pcl whoami --toon
• ./target/debug/pcl workflows --toon
• ./target/debug/pcl schema list --toon
• ./target/debug/pcl api manifest --toon