Build TermKit Studio and TermSpec 0.2 foundation

[ZilaiWang]

What changed

• introduce TermSpec 0.2 concept-first candidate, ChangeSet, review, revision, source and corpus contracts
• add the Alembic-backed local workspace and atomic canonical write workflow
• add the React/FastAPI TermKit Studio workspaces for Concepts, Candidates, Review, Sources, Relations, Exchange, Runtime and Releases
• add CSV/XLSX/TBX/SKOS exchange planning, OpenRefine reconciliation, runtime compilation and benchmark support
• package production Studio assets inside the Python wheel
• rewrite the English and Chinese README files with real product screenshots and task-oriented documentation

Why

This moves TermKit from a terminology-library foundation to the long-term local-first terminology engineering architecture described in the accepted Studio design. Canonical YAML/JSONL remains the source of truth while curation, review and runtime indexes stay derived and auditable.

Validation

• uv run python scripts/check_architecture.py
• uv run ruff check .
• uv run mypy src
• uv run python scripts/export_schemas.py --check
• uv run pytest --cov --cov-report=term-missing — 53 passed, 85.31% coverage
• bun run check && bun run test && bun run build
• uv run python scripts/embed_studio_assets.py --check
• uv build
• browser walkthrough of all Studio workspaces with no console errors or warnings