fix(self-improving-agent): use CLAUDE_PLUGIN_ROOT for hook paths

Relative paths (./hooks/error-capture.sh) resolve against the project
working directory, not the plugin root. Replaced with
${CLAUDE_PLUGIN_ROOT}/hooks/error-capture.sh in both hooks.json and
settings.json.

Fixes #392

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

engineering-team/self-improving-agent/hooks/hooks.json

@@ -6,7 +6,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "./hooks/error-capture.sh"
+            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/error-capture.sh"
           }
         ]
       }

engineering-team/self-improving-agent/settings.json

@@ -18,7 +18,7 @@
   },
   "hooks": {
     "PostToolUse": {
-      "Bash": "hooks/error-capture.sh"
+      "Bash": "${CLAUDE_PLUGIN_ROOT}/hooks/error-capture.sh"
     }
   },
   "agents": [