remove :message-store-api and migrate functionality to :journal-api and :reflection-api

- Removed `:message-store-api` module and associated classes (ConversationStore, ReflectionStore, Ids, etc.).
- Migrated reusable components to `:journal-api` (conversation-related) and `:reflection-api` (reflection-related).
- Updated imports and module dependencies across all projects to reflect new structure.
- Adjusted build scripts and tests for compatibility with the new APIs.

context-ksqlite/src/commonMain/kotlin/pw/binom/agentik/context/ksqlite/KsqliteContextStore.kt

@@ -4,7 +4,7 @@ import kotlinx.serialization.json.Json
 import pw.binom.agentik.context.ContextStore
 import pw.binom.agentik.context.WorkingMemoryEntry
 import pw.binom.agentik.context.WorkingMemoryRow
-import pw.binom.agentik.messageStore.Ids
+import pw.binom.agentik.journal.Ids
 import pw.binom.db.ksqlite.SQLiteConnection
 import pw.binom.db.ksqlite.SQLitePreparedStatement
 import kotlin.time.Clock