feat(client): client-side caching for conversation list via agent.outbox events

Adds `agent.conversationStore` (read-only view on `conversation` table) to
the :proto Agent interface, plus `agent.renameConversation(id, title?)`
command. Client-side cache in :client is built from a snapshot
(`remote.listFlow(0)` → `local.upsert(...)`) + live updates via
`outbox.agentEvents()` (Created/Deleted/Renamed/Touched).

Changes:
- :journal-api — split `ConversationStore` (read-only: get/list) and
  `MutableConversationStore` (CRUD: upsert/delete/rename/touch);
  `ConversationStore` gained `listFlow` (cold-flow paging via `list`).
- :outbox-api — `AgentEvent.Touched(date, id, updatedAt)` event so
  client cache stays fresh after `send()` (which bumps `updatedAt`).
- :proto.Agent — added `conversationStore: ConversationStore` property,
  added `renameConversation(id, title?): Instant?` command, removed
  `getConversations(offset, limit)` (now: `conversationStore.list(...)`).
- :server — `GET /conversations` now returns `List<ConversationRecord>`
  (lightweight metadata, no handle/image-support flags); `PATCH
  /conversations/{id}` uses `agent.renameConversation` and returns
  the updated `ConversationRecord`.
- :journal-inmemory — expanded targets to jvm+macos+linux+mingw (matches
  :client); moved `InMemoryMutableConversationStore` here from
  :storage-inmemory so :client can use it without pulling ios targets.
- :storage-inmemory — depends on :journal-inmemory.
- :storage-ksqlite — pre-staged rename `KsqliteConversationStore` →
  `KsqliteMutableConversationStore` to match the new interface split.
- :standalone — `ChatAgent` exposes `conversationStore` as a read-only
  view of its `mutableConversationStore`; emits `AgentEvent.Touched`
  after each `send()` (after `conversationStore.touch(id, ts)`).
- :client — new `HttpConversationStore` (read-only HTTP impl);
  `AgentikAgent` wraps the agent with `wrapWithLocalConversationCache`
  so the client sees an in-memory cache (snapshot + outbox events)
  instead of direct HTTP. Cache scope + HttpClient + background job
  all cancelled in `agent.close()`.
- :client/README — new «Кэш списка бесед» section with the
  `listFlow → upsert` / `agentEvents → apply` pattern and a note that
  `conversationStore` is read-only (writes only via Agent commands).

All 96 jvmTest tasks green.

server/src/commonMain/kotlin/pw/binom/agentik/server/Routes.kt

@@ -38,7 +38,7 @@ internal fun Route.agentikRoutes(agent: Agent) {
     get("/conversations") {
         val offset = call.request.queryParameters["offset"]?.toIntOrNull() ?: 0
         val limit = call.request.queryParameters["limit"]?.toIntOrNull() ?: Agent.PAGE_SIZE
-        call.respond(agent.getConversations(offset, limit).map { it.snapshot() })
+        call.respond(agent.conversationStore.list(offset, limit))
     }
 
     post("/conversations") {
@@ -63,14 +63,15 @@ internal fun Route.agentikRoutes(agent: Agent) {
 
     patch("/conversations/{id}") {
         val id = call.parameters["id"]!!
-        val c = agent.getConversation(id)
-        if (c == null) {
+        val req = call.receive<RequestRename>()
+        val newUpdatedAt = agent.renameConversation(id, req.title)
+        if (newUpdatedAt == null) {
             call.respond(HttpStatusCode.NotFound)
             return@patch
         }
-        val req = call.receive<RequestRename>()
-        c.rename(req.title)
-        call.respond(c.snapshot())
+        // Возвращаем обновлённый record (лёгкая метадата, не snapshot handle'а).
+        val rec = agent.conversationStore.get(id)!!
+        call.respond(rec)
     }
 
     post("/conversations/{id}/messages") {

server/src/commonTest/kotlin/pw/binom/agentik/server/BearerTokenTest.kt

@@ -13,6 +13,7 @@ import io.ktor.server.engine.embeddedServer
 import io.ktor.server.routing.routing
 import kotlinx.coroutines.flow.emptyFlow
 import kotlinx.coroutines.runBlocking
+import pw.binom.agentik.journal.ConversationStore
 import pw.binom.agentik.journal.JournalStore
 import pw.binom.agentik.journal.MessageRecord
 import pw.binom.agentik.outbox.CommonEvent
@@ -53,10 +54,15 @@ class BearerTokenTest {
             override suspend fun earliestEventDate(): Instant = Instant.DISTANT_PAST
             override fun close() {}
         }
+        override val conversationStore: ConversationStore = object : ConversationStore {
+            override suspend fun get(id: String) = null
+            override suspend fun list(offset: Int, limit: Int) = emptyList<pw.binom.agentik.journal.ConversationRecord>()
+            override fun close() {}
+        }
         override fun createConversation(temp: Boolean): Conversation = TODO("not needed by tests")
         override suspend fun getConversation(id: String): Conversation? = null
         override suspend fun deleteConversation(id: String): Boolean = false
-        override suspend fun getConversations(offset: Int, limit: Int): List<Conversation> = emptyList()
+        override suspend fun renameConversation(id: String, title: String?): Instant? = null
         override fun close() {}
     }