feat(ensi-core): Cargo workspace scaffold + domain entities + port traits

[renatobardi]

Summary

Implements T-001, T-002, and T-003 for the ensi project:

• Cargo workspace with 8 crates (ensi-core, ensi-db, ensi-events, ensi-pipeline, ensi-server, ensi-daemon, ensi-frontend, ensi-cli) — other crates are stubs
• Domain entities (T-002): Workspace, Member, Agent, Project, Issue, PipelineState, Task, TaskMessage, Artifact, Comment, Pat, DaemonToken with full serde/uuid/chrono support and CoreError via thiserror
• Port traits (T-003): All 11 async traits with Result<_, CoreError> — IssueRepository, ProjectRepository, WorkspaceRepository, MemberRepository, AgentRepository, TaskRepository, ArtifactRepository, PipelineRepository, EventPublisher, AgentExecutor, ArtifactStore

Acceptance criteria covered

• All 11 port traits defined as async in ensi-core::ports
• All domain entities defined as pure Rust structs in ensi-core::domain
• CoreError enum with all necessary variants
• No I/O or framework dependencies in ensi-core (only thiserror, serde, uuid, chrono, serde_json)
• cargo check -p ensi-core passes clean

Issues

• Closes REN-15 (T-003: port traits)
• Covers REN-14 (T-002: domain entities, prerequisite)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud