Unify gt prime to call bd prime and mail check

gt prime now internally runs:
- bd prime (beads workflow context)
- gt mail check --inject (mail injection)

This allows a single SessionStart hook to provide complete agent context.
Also added PreCompact and UserPromptSubmit hooks to settings.json.

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

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

.claude/settings.json

@@ -10,6 +10,28 @@
           }
         ]
       }
+    ],
+    "PreCompact": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gt prime"
+          }
+        ]
+      }
+    ],
+    "UserPromptSubmit": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gt mail check --inject"
+          }
+        ]
+      }
     ]
   }
 }