fix(background-agent): inherit parent session directory for background tasks

Background tasks were defaulting to $HOME instead of the parent session's
working directory. This caused background agents to scan the entire home
directory instead of the project directory, leading to:
- High CPU/memory load from scanning unrelated files
- Permission errors on system directories
- Task failures and timeouts

The fix retrieves the parent session's directory before creating a new
background session and passes it via the query.directory parameter.

Files modified:
- manager.ts: Look up parent session directory in launch()
- call-omo-agent/tools.ts: Same fix for sync mode
- look-at/tools.ts: Same fix for look_at tool
- sisyphus-task/tools.ts: Same fix + interface update for directory prop
- index.ts: Pass directory to sisyphusTask factory

src/features/background-agent/manager.ts

@@ -75,11 +75,23 @@ export class BackgroundManager {
 
     await this.concurrencyManager.acquire(concurrencyKey)
 
+    const parentSession = await this.client.session.get({
+      path: { id: input.parentSessionID },
+    }).catch((err) => {
+      log(`[background-agent] Failed to get parent session: ${err}`)
+      return null
+    })
+    const parentDirectory = parentSession?.data?.directory ?? this.directory
+    log(`[background-agent] Parent dir: ${parentSession?.data?.directory}, using: ${parentDirectory}`)
+
     const createResult = await this.client.session.create({
       body: {
         parentID: input.parentSessionID,
         title: `Background: ${input.description}`,
       },
+      query: {
+        directory: parentDirectory,
+      },
     }).catch((error) => {
       this.concurrencyManager.release(concurrencyKey)
       throw error