Migration guides

One guide per release that has breaking changes. Adopters jumping multiple versions follow the guides in chronological order.

• v0.11.0
• v0.10.0
• v0.9.0
• v0.6.0
• v0.5.0
• v0.4.02026-05-20

  Author-SDK reshape (`*Node` → `*JobNode`, typed `Dep`/`WorkDep` for `Needs`, `CacheOptions` rename, spawn / risk APIs reshaped), package layout finalized (`orchestrator/` → `internal/`, `logs/` → `pkg/logs/`, `secrets/` → `internal/`, several others), CLI flag renames + retirements, `--json` / `--pretty` aliases dropped in favor of canonical `-o`/`--output`, `pipelines.yaml` `group:` field removed. Many breaking changes; each section in the linked guide is mechanical.