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>

skills/orch-change-feature/SKILL.md

@@ -0,0 +1,42 @@
+---
+name: orch-change-feature
+description: Orchestrate altering an existing, working feature to new desired behavior — update its tests to the new spec, change the implementation to match, review, and gated commit. Use when behavior is not broken but should be different.
+origin: ECC
+---
+
+# orch-change-feature
+
+Actor · action · target: **orch · change · feature**. Thin wrapper over the
+shared engine in [`orch-pipeline`](../orch-pipeline/SKILL.md).
+
+## When to Use
+
+- An existing feature **works**, but the desired behavior is different ("change",
+  "adjust", "make it also …", "instead of X do Y").
+- Distinguish from siblings:
+  - **not** broken → not `orch-fix-defect` (no bug to reproduce).
+  - **not** new → not `orch-add-feature` (the capability already exists).
+
+## Operation settings
+
+- **Default size floor:** small — most tweaks are a function or two.
+- **Phase mask:** 0 → (1 only if the new behavior needs research) → light 2 →
+  4 → 5 → 6.
+- **First move (phase 4):** update the *existing* tests to express the new
+  desired behavior, then change the implementation until they pass. Changing the
+  tests first is what separates a tweak from a fix.
+
+## How It Works
+
+1. Run the `orch-pipeline` engine with the settings above.
+2. Keep the plan light — only `standard`+ size warrants the full `planner` pass.
+3. Stop at **Gate 1** (plan / changed-test approval) and **Gate 2** (pre-commit).
+4. Add `security-reviewer` if the change touches a security trigger.
+
+## Example
+
+```
+orch-change-feature: make nws-poller alert at 2 warnings instead of 3
+→ update threshold tests to new spec → change impl to green
+→ code-review → commit  [GATE 2: confirm]
+```