Memory search: project-scoped auto-filter

## Friction F-SK-04

`memory_search` and `memory_auto_match` return memories from all projects/sessions. In a project-specific context (FraudDetect), cross-project memories add noise.

## Proposal

- `memory_auto_match` should default to current project scope
- Add `project` filter parameter to `memory_search`
- Or: auto-detect project from working directory and filter by `scope=project`