fix(post-update): clear Claude plugin cache on update

The Claude plugin cache at ~/.claude/plugins/cache/leo-claude-mktplace/
holds versioned copies of .mcp.json files. When we update .mcp.json
to use run.sh instead of direct python paths, the cache retains old
versions, causing MCP servers to fail.

Now post-update.sh clears this cache, forcing Claude to read fresh
configs from the installed marketplace on next session start.

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

plugins/projman/hooks/startup-check.sh

@@ -10,6 +10,19 @@ PLUGIN_ROOT="${CLAUDE_PLUGIN_ROOT:-$(dirname "$(dirname "$(realpath "$0")")")}"
 # Marketplace root is 2 levels up from plugin root (plugins/projman -> .)
 MARKETPLACE_ROOT="$(dirname "$(dirname "$PLUGIN_ROOT")")"
 VENV_REPAIR_SCRIPT="$MARKETPLACE_ROOT/scripts/venv-repair.sh"
+PLUGIN_CACHE="$HOME/.claude/plugins/cache/leo-claude-mktplace"
+
+# ============================================================================
+# Clear stale plugin cache (MUST run before MCP servers load)
+# ============================================================================
+# The cache at ~/.claude/plugins/cache/ holds versioned .mcp.json files.
+# After marketplace updates, cached configs may point to old paths.
+# Clearing forces Claude to read fresh configs from installed marketplace.
+
+if [[ -d "$PLUGIN_CACHE" ]]; then
+    rm -rf "$PLUGIN_CACHE"
+    # Don't output anything - this should be silent and automatic
+fi
 
 # ============================================================================
 # Auto-repair MCP venvs (runs before other checks)