Documents what the code already does (no behavior change): GTI_FISCAL_VERSION
(Hub) and the Agent's own version are separate numbers with separate release
cycles; central.app.installation_identity.reference_agent_version() already
compares an Agent's heartbeat version against the highest PUBLISHED Windows
AgentRelease, never against the Hub's version - verified against
test_version_reference.py. Also documents that there is no real minimum-
version connection gate today (only SCHEMA_FINGERPRINT is enforced) and where
one would go if ever needed.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
