refactor(app): introduce attachment storage layer and draft lifecycle management

Replace inline data-URL image handling with a persistent attachment storage service, add draft lifecycle states (active/abandoned/sent) with generation tracking, and update fetchAgent to return project placement alongside agent snapshots.

packages/app/src/stores/create-flow-store.ts

@@ -1,28 +1,77 @@
 import { create } from "zustand";
 import type { UserMessageImageAttachment } from "@/types/stream";
 
+export type CreateFlowLifecycleState = "active" | "abandoned" | "sent";
+
 type PendingCreateAttempt = {
+  draftId: string;
   serverId: string;
   agentId: string | null;
-  messageId: string;
+  clientMessageId: string;
   text: string;
   timestamp: number;
+  lifecycle: CreateFlowLifecycleState;
   images?: UserMessageImageAttachment[];
 };
 
 type CreateFlowState = {
   pending: PendingCreateAttempt | null;
-  setPending: (pending: PendingCreateAttempt) => void;
+  setPending: (
+    pending: Omit<PendingCreateAttempt, "lifecycle">
+  ) => void;
   updateAgentId: (agentId: string) => void;
+  markLifecycle: (lifecycle: CreateFlowLifecycleState) => void;
+  rekeyDraft: (input: { fromDraftId: string; toDraftId: string }) => void;
   clear: () => void;
 };
 
 export const useCreateFlowStore = create<CreateFlowState>((set) => ({
   pending: null,
-  setPending: (pending) => set({ pending }),
+  setPending: (pending) =>
+    set({
+      pending: {
+        ...pending,
+        lifecycle: "active",
+      },
+    }),
   updateAgentId: (agentId) =>
-    set((state) =>
-      state.pending ? { pending: { ...state.pending, agentId } } : state
-    ),
+    set((state) => {
+      if (!state.pending || state.pending.agentId === agentId) {
+        return state;
+      }
+      return {
+        pending: {
+          ...state.pending,
+          agentId,
+        },
+      };
+    }),
+  markLifecycle: (lifecycle) =>
+    set((state) => {
+      if (!state.pending || state.pending.lifecycle === lifecycle) {
+        return state;
+      }
+      return {
+        pending: {
+          ...state.pending,
+          lifecycle,
+        },
+      };
+    }),
+  rekeyDraft: ({ fromDraftId, toDraftId }) =>
+    set((state) => {
+      if (!state.pending || state.pending.draftId !== fromDraftId) {
+        return state;
+      }
+      if (state.pending.draftId === toDraftId) {
+        return state;
+      }
+      return {
+        pending: {
+          ...state.pending,
+          draftId: toDraftId,
+        },
+      };
+    }),
   clear: () => set({ pending: null }),
 }));