Fix(logging): cut per-task log noise and close the incident gaps from the 2026-09-03 trace

[GuillaumeSachet]

• Toolkit build logs one DEBUG line instead of four INFO families plus one per wrapped tool
• Each tool call logs once, on completion, with its argument keys; the call-start line is DEBUG
• m2m handshake lines (AssociateTask minted, StartStream accepted, dial-back received) move to DEBUG; the timeout warning counts only domain frames, with stream.resume in the shared sentinel set
• Task lifecycle keeps Task accepted, Starting/finished/cancelled module and Task done at INFO; gateway, task-manager, runner, servicer, adapter and agui trace goes to DEBUG; setup access DENIED and secret-fetch failures are WARNING; TODO(validate) markers removed
• INPUT_VALIDATION_ERROR names the failing field and reason (first three errors, bounded)
• Session.cancelled is set when the module task is cancelled and ModuleToolkit refuses further tool calls
• A tool stream carrying a fatal stream.error is reported as a failure even after domain outputs
• SUBAGENT_FINISHED and SUBAGENT_ERROR carry elapsed_s
• Bump version to 1.0.4.dev0