Write the parameter coherence guide

[luchobonatti]

User story / Problem statement

No contract validates the oracle's cooldown and staleness horizon against the vault's notice period. If the attestation cadence is slower than the heartbeat, the feed goes Stale exactly when a matured generation needs to be struck, and settlement stalls until the next attestation. No contract catches this, so it belongs in the runbook.

Expected outcome

An operator table with safe defaults, and a system test that proves them.

Acceptance criteria

• the relation written out: attestation cadence must guarantee a Valid feed is reachable whenever a generation past its notice is due to be struck
• heartbeat_secs, cooldown_secs and notice_secs given safe defaults, with the reasoning
• the TTL horizons folded in, since set_notice_secs can widen notice past them
• the incoherent combinations named, with the symptom each produces
• a system test that runs a full cycle at the recommended values
• the table lands in the runbook

Technical notes

The parameters are admin-mutable at runtime: set_notice_secs on the vault and set_config on the oracle. A coherent deployment can drift into an incoherent one through a legitimate parameter change, so the guide has to cover changes, not just initial values.

Worth stating in the guide: the symptom of an incoherent set is a fulfill that reverts on a Stale feed, which looks like an oracle failure and is not.