feat: add orch-* orchestrator skill family (#2153)

* feat: add orch-* orchestrator skill family

Lightweight wrappers that orchestrate existing ECC agents through a gated Research -> Plan -> TDD -> Review -> Commit pipeline, right-sized per task.

- orch-pipeline: shared engine (phases, size classifier, two gates, agent map)
- orch-add-feature/change-feature/fix-defect/refine-code/build-mvp: thin wrappers delegating to the engine

* chore: register orch-* family in catalog, command registry, and agent.yaml (post-rebase onto green main)

---------

Co-authored-by: ECC Test <ecc@example.test>

commands/orch-add-feature.md

@@ -0,0 +1,36 @@
+---
+description: Orchestrate building a brand-new feature end to end — research, plan, TDD, review, gated commit. Wrapper that kicks off the orch-add-feature skill.
+---
+
+# /orch-add-feature
+
+Manually launch the **orch-add-feature** orchestrator: a gated
+Research → Plan → TDD → Review → Commit pipeline for net-new capability.
+
+## Usage
+
+```
+/orch-add-feature <what to add>
+```
+
+Examples:
+
+```
+/orch-add-feature add OAuth2 login to nws-poller
+/orch-add-feature support CSV export in the dashboard
+```
+
+## What It Does
+
+Invoke the `orch-add-feature` skill with `$ARGUMENTS` as the request. The skill
+(via the shared `orch-pipeline` engine) will:
+
+1. Classify size and state the tier in one line.
+2. Research existing libraries/patterns, then plan a `task_list`. → **GATE 1** (approve plan).
+3. TDD each task (new failing tests → green), then `code-reviewer`
+   (+ `security-reviewer` if a security trigger is touched).
+4. Commit as conventional `feat:` commits. → **GATE 2** (confirm before commit).
+
+Honor both gates — do not write implementation before Gate 1, do not commit before Gate 2.
+
+If `$ARGUMENTS` is empty, ask the user what capability to add.