feat(sessions): add human work logs

[Harry19081]

Summary

• add an append-only Human session type surfaced as Work logs in the regular session creator and sidebar
• support optional persisted titles, repeated notes, skills, session mentions, and standard session navigation/deletion
• reuse the regular creator controls and shared Work-item activity timeline, with localized UI across supported languages
• include architecture, frontend UI, and acceptance documentation

Validation

• pnpm typecheck
• 68 focused Vitest tests across RPC schemas, routing, mentions, sidebar grouping, creator actions, and rendered timelines
• cargo test --manifest-path src-tauri/Cargo.toml -p org2 human --lib
• cargo test --manifest-path src-tauri/Cargo.toml -p session_persistence init_session_tables_creates_human_session_entry_schema
• pre-commit lint-staged, scoped TypeScript validation, and strict Clippy for agent_core, org2, and session_persistence