Refactor event payload handling across adapters

- Introduced `event-payload` crate to centralize event payload definitions.
- Updated NATS and PostgreSQL adapters to use the new `EventPayload` type.
- Removed redundant event payload definitions and conversion implementations from NATS and PostgreSQL adapters.
- Simplified SQLite event queue to utilize the new `EventPayload`.
- Refactored wiring functions for PostgreSQL and SQLite to improve database connection handling and migration.
- Cleaned up presentation and worker crates by removing unused event publisher dependencies and related wiring functions.

Cargo.toml

@@ -16,6 +16,7 @@ members = [
     "crates/adapters/activitypub",
     "crates/adapters/activitypub-base",
     "crates/adapters/export",
+    "crates/adapters/event-payload",
     "crates/adapters/nats",
     "crates/application",
     "crates/domain",
@@ -67,6 +68,7 @@ template-askama = { path = "crates/adapters/template-askama" }
 activitypub = { path = "crates/adapters/activitypub" }
 activitypub-base = { path = "crates/adapters/activitypub-base" }
 doc = { path = "crates/doc" }
+event-payload = { path = "crates/adapters/event-payload" }
 nats = { path = "crates/adapters/nats" }
 sqlite-event-queue = { path = "crates/adapters/sqlite-event-queue" }
 postgres-event-queue = { path = "crates/adapters/postgres-event-queue" }