feat: DISABLE_DATAFORGE / DISABLE_GLOBAL_SEARCH env kill-switches — skip the capability probe
AND its tools entirely (no network / no token spend), even where available; describe-entity
falls back to the active CRUD backend. Wired via ServerConfig (cli + index). Tests cover both
flags incl. describe-entity not routing through DataForge when disabled.
docs: CHANGELOG.md (from 0.3.0); AGENTS.md mandatory release checklist (bump→tag→publish),
engineering principles (SOLID/GRASP/Clean Code/patterns), tests-are-part-of-done; README flags.

432 tests green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>