fix: move mcp_servers to metadata.json to prevent silent plugin.json rejection

Claude Code's strict schema validation silently rejects plugins with unknown
root-level fields in plugin.json (anthropics/claude-code#20409).
Moved mcp_servers to separate metadata.json files.
Updated install/uninstall/list scripts to read from new location.
Added cache clearing to switch-profile.sh.

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

scripts/switch-profile.sh

@@ -12,7 +12,9 @@ case "${1:-lean}" in
   lean)
     cp "$MARKETPLACE_DIR/marketplace-lean.json" "$MARKETPLACE_DIR/marketplace.json"
     cp "$ROOT_DIR/.mcp-lean.json" "$ROOT_DIR/.mcp.json"
+    rm -rf ~/.claude/plugins/cache/
     echo "Switched to LEAN profile (6 plugins, 1 MCP server)"
+    echo "Plugin cache cleared."
     echo ""
     echo "Plugins: projman, git-flow, pr-review, clarity-assist, code-sentinel, doc-guardian"
     echo "MCP: gitea only"
@@ -22,7 +24,9 @@ case "${1:-lean}" in
   full)
     cp "$MARKETPLACE_DIR/marketplace-full.json" "$MARKETPLACE_DIR/marketplace.json"
     cp "$ROOT_DIR/.mcp-full.json" "$ROOT_DIR/.mcp.json"
+    rm -rf ~/.claude/plugins/cache/
     echo "Switched to FULL profile (12 plugins, 5 MCP servers)"
+    echo "Plugin cache cleared."
     echo ""
     echo "Plugins: all"
     echo "MCP: gitea, netbox, data-platform, viz-platform, contract-validator"