fix(data-platform): use separate hooks.json file (not inline)

Previous fix was wrong. Hooks should be in separate hooks/hooks.json
file (auto-discovered), NOT inline in plugin.json.

Pattern matches working plugins: projman, pr-review, claude-config-maintainer

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

plugins/data-platform/.claude-plugin/plugin.json

@@ -18,14 +18,6 @@
     "etl",
     "dataframe"
   ],
-  "hooks": {
-    "SessionStart": [
-      {
-        "type": "command",
-        "command": "${CLAUDE_PLUGIN_ROOT}/hooks/startup-check.sh"
-      }
-    ]
-  },
   "commands": ["./commands/"],
   "mcpServers": ["./.mcp.json"]
 }

plugins/data-platform/hooks/hooks.json

@@ -0,0 +1,10 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "type": "command",
+        "command": "${CLAUDE_PLUGIN_ROOT}/hooks/startup-check.sh"
+      }
+    ]
+  }
+}