refactor(monorepo): extract inbox and orch runtimes

docs/roadmaps/active/skill-workspace-monorepo-migration.md

@@ -27,7 +27,7 @@
 - [x] create or adopt an active execution roadmap for the migration workstream
 - [x] Phase 1: bootstrap `go.work`, expanded workspace manifests, package roots, and declarative skill bundle metadata
 - [x] Phase 2: extract shared coordination code into `packages/coord-core`
-- [ ] Phase 3: extract `inbox-runtime` and `orch-runtime`
+- [x] Phase 3: extract `inbox-runtime` and `orch-runtime`
 - [ ] Phase 4: extract `orchd-runtime`
 - [ ] Phase 5: import `repo-memory-runtime` and add `skills/repo-memory`
 - [ ] Phase 6: remove root runtime ownership and normalize package-based packaging
@@ -54,4 +54,4 @@
 
 ## Next Step
 
-- start Phase 3 by moving `inbox` and `orch` into package-owned runtimes on top of the now-shared `packages/coord-core` kernel
+- start Phase 4 by moving the HTTP/query/web backend runtime into `packages/orchd-runtime` on top of the extracted `coord-core`, `inbox-runtime`, and `orch-runtime` packages