feat(local): model local command log boundary

Define local/offline truth as commands, domain events, and projections rather than stored DOM patches or EffectBatch payloads, and wire the techdemo through a local command-to-projection-to-effect flow.

req: local/001

req: local/002

req: local/003

req: local/004

req: examples/001

docs/recipes/local-command-log.md

@@ -0,0 +1,38 @@
+# Recipe: local command log
+
+A hemx app may feel local-first without making hemx core a client database or
+sync framework. The local artifact is an app-owned command/event log plus a
+projection; hemx effects are rendered output, not stored truth. req: local/001
+req: local/002
+
+## Shape
+
+```text
+user intent
+→ LocalCommand
+→ domain validation
+→ LocalEvent
+→ Projection
+→ hemx EffectBatch
+```
+
+The log may live in memory, IndexedDB, SQLite, a native host store, or another
+app-chosen persistence layer. That storage choice is not hemx core. req: local/002
+
+## Replay and sync
+
+Replaying local work to a server, remote AI/STT gateway, backup target, or peer
+sync engine is explicit product policy. The app decides what can be queued,
+exported, deleted, reconciled, retried, rejected, or redacted. A local projection
+can render immediate feedback while those decisions remain pending. req: local/003
+
+## Boundary
+
+Do not persist DOM patches as truth. Do not persist `EffectBatch` payloads as the
+local application log. Those are render instructions produced after app/domain
+code accepts commands and projects events. req: local/001 req: local/004
+
+Use `hemx-host` only when the local log needs device or shell capabilities such
+as secure storage, files, haptics, microphone, or notifications. The host still
+returns facts; app code still owns the command/event/projection policy. req:
+host/002 req: local/003