docs(dox): build out the DOX AGENTS.md hierarchy

Root Child DOX Index assembled, plus a per-module AGENTS.md across the tree
(core/*, infrastructure/*, apps/*, testing/*, and docs/examples/frontend/etc),
each following the DOX section shape: Purpose, Ownership, Local Contracts,
Work Guidance, Verification, Child DOX Index.

infrastructure/persistence/AGENTS.md

@@ -0,0 +1,31 @@
+# infrastructure/persistence/
+
+## Purpose
+
+Event store adapters for the correx event log. Provides `SqliteEventStore` (durable, production) and `InMemoryEventStore` (tests/dev). Also contains `LiveArtifactRepository`, which projects artifact state from the event log via `core:artifacts`.
+
+## Ownership
+
+Sole persistence adapter for `core:events` (`EventStore`). No other infrastructure module may write to the event log.
+
+## Local Contracts
+
+- `SqliteEventStore` implements `EventStore` from `core:events`; the SQLite file is the authoritative event log.
+- `InMemoryEventStore` is for tests only — not suitable for production use.
+- `LiveArtifactRepository` implements `ArtifactRepository` from `core:artifacts` by replaying events; it never persists state independently (invariant #1).
+- Schema migrations are the responsibility of this module; `JDBCHelper` owns connection utilities.
+- The event log is append-only: no updates or deletes to existing rows.
+
+## Work Guidance
+
+Standard adapter rules apply (see parent `AGENTS.md`). All JDBC calls go in `withContext(Dispatchers.IO)`.
+
+## Verification
+
+```
+./gradlew :infrastructure:persistence:test --rerun-tasks
+```
+
+## Child DOX Index
+
+No child AGENTS.md (leaf module).