Improve attachment memory safety, downloads, and high-memory alert UX.

Stream large receives to disk with chunk acks to cap renderer RAM, evict
off-screen display blobs, and route exports through a disk-aware download
service. Fix the high-memory dialog (backdrop dismiss, copy, log actions),
allow diagnostics paths in the path jail, and restore persisted image
hydration after reload.

Co-authored-by: Cursor <cursoragent@cursor.com>

toju-app/src/app/domains/attachment/application/services/attachment-runtime.store.ts

@@ -12,6 +12,7 @@ export class AttachmentRuntimeStore {
   private pendingRequests = new Map<string, Set<string>>();
   private chunkBuffers = new Map<string, (ArrayBuffer | undefined)[]>();
   private chunkCounts = new Map<string, number>();
+  private announcedHostsByAttachment = new Map<string, Set<string>>();
 
   touch(): void {
     this.updated.set(this.updated() + 1);
@@ -66,6 +67,25 @@ export class AttachmentRuntimeStore {
     return this.originalFiles.get(key);
   }
 
+  deleteOriginalFile(key: string): void {
+    this.originalFiles.delete(key);
+  }
+
+  addAnnouncedHost(requestKey: string, peerId: string): void {
+    const hosts = this.announcedHostsByAttachment.get(requestKey) ?? new Set<string>();
+
+    hosts.add(peerId);
+    this.announcedHostsByAttachment.set(requestKey, hosts);
+  }
+
+  getAnnouncedHosts(requestKey: string): Set<string> {
+    return this.announcedHostsByAttachment.get(requestKey) ?? new Set();
+  }
+
+  deleteAnnouncedHosts(requestKey: string): void {
+    this.announcedHostsByAttachment.delete(requestKey);
+  }
+
   findOriginalFileByFileId(fileId: string): File | null {
     for (const [key, file] of this.originalFiles) {
       if (key.endsWith(`:${fileId}`)) {
@@ -160,5 +180,11 @@ export class AttachmentRuntimeStore {
         this.cancelledTransfers.delete(key);
       }
     }
+
+    for (const key of Array.from(this.announcedHostsByAttachment.keys())) {
+      if (key.startsWith(scopedPrefix)) {
+        this.announcedHostsByAttachment.delete(key);
+      }
+    }
   }
 }