docs(intake): ground initiatives in owning docs, not session anchors

[ruby-dlee]

Why

A two-day "Firstmate on Azure" push was worked from SESSION-ANCHOR-2026-08-13.md plus one narrow leaf design doc (docs/azure-worker-runtime.md) as if those were the specification. Four of the five owning docs (azure-pilot, azure-runner, azure-validation, azure-crosscheck, azure-workers, ~140KB total) were never opened. Result: one leaf subsystem got optimized, progress was reported against a far narrower scope than the initiative, and a documented limitation of a single compartment was relayed to the captain as a requirement of the whole system.

The generalizable failure is that a session log describes STATE, not INTENT, and it was read as the spec.

What changed

One block added to section 7 Intake, immediately before "Write the brief per section 11":

• find the doc that OWNS the subsystem and read it (this repo's docs declare it outright);
• anchors, checkpoints, handoff notes, completion reports and evidence folders are state, never intent, and resuming from one requires reconciling it against the owning docs;
• enumerate sibling docs when an initiative spans compartments, and never generalize one compartment's documented limitation to the system;
• name the owning docs by path in the brief.

The Azure family is listed explicitly since that is the family the failure hit, and azure-worker-runtime.md is marked as the design leaf under azure-workers.md.

The general form of this rule also went into the machine-global agent instructions, so it applies outside this repo too.

Verification

Doc-only change, 6 lines. The behavior tests that read AGENTS.md all pass locally:
fm-ensure-agents-md, operating-fundamentals, fm-update, lavish-repair, fm-captain-item-check, fm-stow-contract.