fix(hooks): correct venv path in startup-check scripts

The startup hooks were looking for MCP venvs relative to the plugin
directory instead of the marketplace root, causing false "venv missing"
errors on every session start.

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

plugins/pr-review/hooks/startup-check.sh

@@ -7,7 +7,9 @@ PREFIX="[pr-review]"
 
 # Check if MCP venv exists
 PLUGIN_ROOT="${CLAUDE_PLUGIN_ROOT:-$(dirname "$(dirname "$(realpath "$0")")")}"
-VENV_PATH="$PLUGIN_ROOT/mcp-servers/gitea/.venv/bin/python"
+# MCP servers are at marketplace root, not inside plugin
+MARKETPLACE_ROOT="$(dirname "$(dirname "$PLUGIN_ROOT")")"
+VENV_PATH="$MARKETPLACE_ROOT/mcp-servers/gitea/.venv/bin/python"
 
 if [[ ! -f "$VENV_PATH" ]]; then
     echo "$PREFIX MCP venvs missing - run setup.sh from installed marketplace"