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/cli/src/commands/agent/attach.ts

@@ -118,14 +118,14 @@ export async function runAttachCommand(
   }
 
   try {
-    const agent = await client.fetchAgent(id)
-    if (!agent) {
+    const fetchResult = await client.fetchAgent(id)
+    if (!fetchResult) {
       console.error(`Error: No agent found matching: ${id}`)
       console.error('Use `paseo ls` to list available agents')
       await client.close()
       process.exit(1)
     }
-    const resolvedId = agent.id
+    const resolvedId = fetchResult.agent.id
 
     // Print header
     console.log(`Attaching to agent ${resolvedId.substring(0, 7)}...`)