Keep MCP recall tools storage-read-only

[hjqcan]

Summary

• disable post-recall evolution writes only for standalone and installed MCP memory instances
• keep HTTP bridge, public API, CLI, and hook recall observability unchanged
• add a stale-fact regression proving goodmemory_get_context does not create experiences, proposals, or promotions even when the MCP write tool is enabled

Why

The MCP surface documents its recall tools as read-only. A stale recall through goodmemory_get_context could still persist recall observations and then create evolution proposals and promotions. That changed the SQLite database without invoking goodmemory_remember. This patch aligns the durable behavior with the advertised MCP boundary while preserving the stateful behavior of non-MCP product surfaces.

Verification

• targeted MCP unit suite: 44 passed
• MCP integration suite: 8 passed
• bun test: 6,792 passed, 65 skipped, 0 failed
• bun run test:coverage with pgvector/pgvector:pg16: 6,663 passed, 60 skipped, 0 failed; overall 92.29 percent; storage 94.60 percent
• bun run typecheck
• bun run build
• git diff --check

This is a boundary correction, not benchmark evidence or user-adoption evidence.