fix: remove user-message hook from SessionStart to prevent startup error

The user-message hook exits with code 3 (USER_MESSAGE_ONLY), which Claude
Code interprets as a hook failure, displaying "SessionStart:startup hook
error" on every session start. The context hook already handles injecting
context into the conversation, making the user-message hook redundant.

Removing it eliminates the spurious error message and saves ~60 seconds
of potential timeout on systems where the worker is slow to respond.

Closes #905

plugin/hooks/hooks.json

@@ -31,11 +31,6 @@
             "type": "command",
             "command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/bun-runner.js\" \"${CLAUDE_PLUGIN_ROOT}/scripts/worker-service.cjs\" hook claude-code context",
             "timeout": 60
-          },
-          {
-            "type": "command",
-            "command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/bun-runner.js\" \"${CLAUDE_PLUGIN_ROOT}/scripts/worker-service.cjs\" hook claude-code user-message",
-            "timeout": 60
           }
         ]
       }