Use session-start.sh hook for session_id passthrough (gt-3zsml)

The SessionStart hook now parses stdin JSON to extract session_id
and passes it to gt prime via CLAUDE_SESSION_ID env var.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/settings.json

@@ -9,7 +9,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "gt prime && gt nudge deacon session-started"
+            "command": "bash ~/.claude/hooks/session-start.sh && gt nudge deacon session-started"
           }
         ]
       }