refactor: add exec debug logs and remove unused MCP stats tool

feat: add debug logging for command execution and remove redundant read log

docs: update documentation with dependencies and cleanup

docs: add dependencies section to AGENTS.md

refactor: add Hijack support and update test script

refactor: simplify MCP tools to exec and stats only

refactor: update scripts to support Header-only identity routes

refactor: extract identity package with Scarf and ParseScarf

refactor: consolidate exec logic with SessionExecuter interface

docker: add 1G memory limit to compose and run examples

refactor: rename user_id to owner_id in JSON APIs

refactor: rename userID to ownerID in proto and all consumers

refactor(sandbox): rename userID to ownerID and extract sessionKey()

refactor: rename UserID to OwnerID, X-User-Id to X-Owner-Id

refactor: extract Scarf parsing and key generation to context package