Explain LabNote’s continuity and audit boundaries

[Wonderforge-Lab]

Phase 2: explain the distinction

Expands WHY_LABNOTE.md in English and Simplified Chinese.

It now separates:

• model context from selected project continuity;
• automatic agent memory from a visible, human-controlled project record;
• repository context files from a route through ongoing work; and
• runtime observability from a project-level audit trail.

It also makes the boundary around LabNote’s rails explicit: they make coordination legible and reviewable; they do not make a model deterministic or infallible.

No workflow, schema or runtime behaviour changes.