`_run_execution_chain` read `get_plugin_manager()._middleware` directly,
bypassing the lazy discovery every other delivery entry point gained in
the #64178 parity work, so `tool_execution`/`llm_execution` middleware
registered by user plugins silently failed to fire (fail-open) on
surfaces that never run discovery at startup: query mode `chat -q`/`-z`,
cron delivery, dashboard, TUI slash workers. Route it through
`_delivery_manager()` like invoke_hook/invoke_middleware/has_middleware.
(cherry picked from commit 06b9d44095733f8e46f40f0331b3f6dff352e98e)
Fixes#105827
Salvages #105832
592163d299