feat: add typed zero-instance discovery flow

[loonghao]

Summary

• route zero local inventory through the Core v1 discovery decision
• keep local and remote zero-instance evidence branches mutually exclusive
• keep support, installation, bootstrap, registration, readiness, and real-host evidence separate
• preserve a conservative exact-match fallback for older CLI releases
• require consent only before mutation or host launch
• bump the Skill suite to 0.19.98 and regenerate distribution metadata

Validation

• python -m unittest discover -s tests -v (57 passed)
• python scripts/validate_repository.py
• python scripts/sync_product_discovery.py --check
• python scripts/build_geo_site.py --check

Dependencies

Public Skill ownership prerequisite #11 is merged. Depends on dcc-mcp/dcc-mcp-core#2419 for the new CLI contract; the documented legacy fallback remains read-only and exact-match gated.

Refs dcc-mcp/dcc-mcp-core#2383.