Path traversal in EverOS /api/v1/memory/add via unvalidated sender_id

Summary

EverOS is a memory runtime for agents. Prior to 1.0.1, EverOS is vulnerable to path traversal in the POST /api/v1/memory/add ingestion endpoint because the per-message sender_id field was not validated as a path-safe identifier, unlike app_id and project_id. During user-memory extraction, sender_id is used as owner_id and joined into the filesystem path where the extracted episode is persisted as a Markdown file, so a sender_id containing ../ sequences could direct writes outside the configured memory root and allow an unauthenticated caller to create or overwrite .md files at locations writable by the server process with partially attacker-influenced content. This issue is fixed in version 1.0.1.