feat: implement explicit sticker history cleanup (TASK-WP5-06)

apps/api/src/projects.ts

@@ -366,6 +366,7 @@ export class ProjectService {
         throw new ProjectError("project_state_conflict", latest);
       }
       this.insertProjectState({ canvasState: canvas, name, projectId: input.projectId, stateVersion: nextVersion }, now);
+      this.rebuildProjectStickerReferences(input.projectId, canvas, now);
       this.database.prepare(`
         INSERT INTO project_state_idempotency (
           owner_id, project_id, idempotency_key, request_hash, response_state_version, created_at
@@ -377,6 +378,25 @@ export class ProjectService {
     return result;
   }
 
+  private rebuildProjectStickerReferences(projectId: string, canvas: CanvasState, now: number) {
+    if (!this.tableExists("project_sticker_asset_refs")) return;
+    this.database.prepare("DELETE FROM project_sticker_asset_refs WHERE project_id = ?").run(projectId);
+    const insert = this.database.prepare(`
+      INSERT INTO project_sticker_asset_refs (reference_id, project_id, stable_id, resource_version, created_at)
+      VALUES (?, ?, ?, ?, ?)
+    `);
+    for (const element of canvas.elements) {
+      if (element.type !== "static_sticker") continue;
+      insert.run(
+        `project:${projectId}:sticker:${element.element_id}`,
+        projectId,
+        element.template_or_asset_id,
+        element.resource_version,
+        now,
+      );
+    }
+  }
+
   trashFailedEmpty(ownerId: string, projectIds: string[]) {
     const uniqueIds = [...new Set(projectIds)];
     if (uniqueIds.length === 0 || uniqueIds.length > projectLimit) throw new ProjectError("generation_state_invalid");
@@ -774,6 +794,16 @@ export class ProjectService {
         FOREIGN KEY (project_id) REFERENCES projects(project_id) ON DELETE CASCADE
       );
       CREATE INDEX IF NOT EXISTS project_resource_files_managed ON project_resource_files(managed_file_id, project_id);
+      CREATE TABLE IF NOT EXISTS project_sticker_asset_refs (
+        reference_id TEXT PRIMARY KEY,
+        project_id TEXT NOT NULL,
+        stable_id TEXT NOT NULL,
+        resource_version TEXT NOT NULL,
+        created_at INTEGER NOT NULL,
+        FOREIGN KEY (project_id) REFERENCES projects(project_id) ON DELETE CASCADE
+      );
+      CREATE INDEX IF NOT EXISTS project_sticker_asset_refs_lookup
+        ON project_sticker_asset_refs (stable_id, resource_version);
       CREATE TABLE IF NOT EXISTS latest_exports (
         project_id TEXT NOT NULL,
         format TEXT NOT NULL CHECK (format IN ('jpg', 'png')),