fix: use double quotes for CLAUDE_PLUGIN_ROOT in SessionStart hook

Replace single quotes with escaped double quotes around
${CLAUDE_PLUGIN_ROOT} in hooks.json so the shell variable expands
correctly on Linux. Single quotes prevent variable expansion,
causing the hook to fail with 'No such file or directory'.

Closes #577

hooks/hooks.json

@@ -6,7 +6,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "'${CLAUDE_PLUGIN_ROOT}/hooks/run-hook.cmd' session-start",
+            "command": "\"${CLAUDE_PLUGIN_ROOT}/hooks/run-hook.cmd\" session-start",
             "async": false
           }
         ]