feat(kit): declare builder.build workflow routing

[briananderson1222]

What this does

Adds two JSON manifests under kits/:

• kits/catalog.json — the kit registry entry that makes the builder kit discoverable in this repository.
• kits/builder/kit.json — the kit manifest declaring workflow_triggers, which routes implementation prompts into the builder.build flow.

The flow-agents workflow-steering hook requires both files to discover a kit: a bare kit.json with no catalog entry is invisible to it. Neither file existed in this repository before this change, so the steering hook rendered no guidance on implementation prompts here.

Rendered steering (verified against the hook's own resolver)

KIT WORKFLOW ROUTE: this user prompt matches implementation-work-detected. Before source edits or implementation commands, use the `builder` kit's `builder.build` workflow. If user-requested-tdd, activate `tdd-workflow`; otherwise activate `deliver`. Keep the session on `builder.build`. Use the public `flow-agents workflow` interface only when it supports that Flow and its Work Item binding; otherwise report an unsupported-runtime blocker. Never call the package-internal writer from skill guidance. Do not bypass ensure-session -> plan-work -> execute-plan -> review-work -> verify-work for matching work. After local verification, continue to release-readiness and learning-review; do not treat local verification as terminal delivery.

Scope

Configuration only — two static JSON files. No source code, no build changes, no runtime behavior change in this repository.

https://claude.ai/code/session_01U8LDoJ4wStU1C3eaEb2xYa