fix: restrict Letta Code triggers to owner-only access

- Gate job with `if: github.actor == greedychipmunk` so only the repo owner can trigger
- Add label and assigned event types for issues/PRs
- Set assignee_trigger to letta-code so assigning the agent activates it
- Add pull_request labeled events for PR label triggers

👾 Generated with [Letta Code](https://letta.com)

Co-Authored-By: Letta Code <noreply@letta.com>

.github/workflows/letta.yml

@@ -1,16 +1,19 @@
 name: Letta Code
 
 on:
+  issues:
+    types: [opened, labeled, assigned]
   issue_comment:
     types: [created]
-  issues:
-    types: [opened, assigned]
+  pull_request:
+    types: [opened, labeled]
   pull_request_review_comment:
     types: [created]
 
 jobs:
   letta:
     runs-on: ubuntu-latest
+    if: github.actor == 'greedychipmunk'
     permissions:
       contents: write
       issues: write
@@ -23,3 +26,4 @@ jobs:
         with:
           letta_api_key: ${{ secrets.LETTA_API_KEY }}
           github_token: ${{ secrets.GITHUB_TOKEN }}
+          assignee_trigger: letta-code