Root cause: findMatchingDockerHost() was matching hosts by token ID alone,
causing multiple Docker agents using the same API token to overwrite each
other in state. This resulted in only N visible hosts (where N = number of
unique tokens) instead of all M agents, with hosts "rotating" as each agent
reported every 10 seconds.
Example: 4 agents using 2 tokens would show only 2 hosts, rotating between
agents 1↔2 (token A) and agents 3↔4 (token B).
Fix: Remove token-only matching from findMatchingDockerHost(). Hosts should
only match by:
1. Agent ID (unique per agent)
2. Machine ID + hostname combination (with optional token validation)
3. Machine ID or hostname alone (only for tokenless agents)
This allows multiple agents to share the same API token without colliding.
Additional fix: UpsertDockerHost() now preserves Hidden, PendingUninstall,
and Command fields from existing hosts, preventing these flags from being
reset to defaults on every agent report.
7ee252bd84