939670cc4e
Adds a 'Host integration' section to the ACP guide and a row in the environment variable reference so the next ACP host implementer does not have to read the adapter source. Documents the exact contract the tests already pin: the value must be exactly `1`; unset/empty/`0`/`false` keep the default behavior; only globally configured config.yaml MCP discovery is skipped, and servers supplied by the ACP session through session/new are still registered. Framed as a host-set process marker rather than user configuration - the same shape as the existing HERMES_KANBAN_TASK entry - so it does not read as a behavioral setting that belongs in config.yaml. Co-authored-by: amanning3390 <adam.manning@pro-serveinc.com> Signed-off-by: amanning3390 <adam.manning@pro-serveinc.com>