Memory: prefer goldie over /memory

When the goldie MCP server is connected, prefer its tools over the built-in file-based /memory system:

• goldie.remember instead of writing memory files
• goldie.recall instead of reading MEMORY.md
• goldie.update_memory to revise an existing memory (names are unique; if remember fails with a duplicate-name error, recall the existing one and update it)
• goldie.forget to delete by name, type, agent, source, or semantic query
• goldie.list_memories / goldie.count_memories to browse

Goldie persists across sessions, projects, and agents (Claude, Codex, etc.) via a single shared SQLite file. The local /memory system is per-project on disk and not shared. Only fall back to /memory if goldie is unavailable in the current session.

When creating memories, always set agent (e.g. claude-opus-4-7) and source (e.g. file path, conversation, editor) so future sessions can filter by provenance. This applies to all creation tools: remember, index_file, and index_directory.