[LogosDB] Add memory management commands (/delete, /list)

Add CLI commands to manage stored memories using new LogosDB v0.2.0 delete/update APIs.

## Proposed Commands

### /delete
Delete memories matching a search query.
Example flow:
Found 2 matches:
[1] id=42 "My commute is 30 minutes"
[2] id=43 "My commute takes 30 minutes"
Delete which? (comma-separated IDs, or all): 42,43
Deleted 2 memories.

### /forget
Delete by exact ID for scripting purposes.

### /list or /memories
Show memory statistics and recent entries with pagination.

### /stats
Quick statistics: live memories, deleted, total count.

## Implementation Notes
- Store IDs returned from logosdb_put() in session cache
- Use logosdb_search() to find candidates for deletion
- Confirm before bulk deletion
- Update semantic_memory_options to track ID mappings

## Acceptance Criteria
- [ ] /delete command with confirmation
- [ ] /forget direct deletion command
- [ ] /list command with pagination
- [ ] /stats quick stats command
- [ ] Store IDs when teaching (cache or metadata file)
- [ ] Handle deleted rows in search (auto-filtered by LogosDB)

## Dependencies
- Requires LogosDB v0.2.0 (issue #8)

## Related Files
- tools/cli/cli.cpp - command parsing and handling
- SPECS.md - CLI documentation