MC-5013

Dependent follow-up for the Iris/Life Manager attention redesign. Dependency: - Start after MC-5011 append-only Telegram send ledger is done and verified. Context: - MC-5003/MC-5004 completed Phase A baseline + first reversible noise-reduction slice. - MC-5011 should provide canonical send evidence. - The attention plan Phase B starts with an Attention Gate MVP: SQLite attention ledger plus a `should_notify` helper before integrating noisy emitters. Goal: Build the minimal reusable Attention Gate foundation without changing live notification routing yet. Scope: - Add a durable SQLite or equivalent local ledger for attention decisions/candidates, separate from the send-success ledger if needed but linkable by source/message id where possible. - Implement a shared `should_notify` helper/API that classifies Tier 0 silent work, Tier 1 digest-only, and Tier 2 interruptive Telegram alerts. - Include core fields needed for audit: timestamp, source/emitter/task, candidate/message class, tier, decision, reason, dedupe/snooze key where available. - Keep integration dry-run/advisory only in this ticket; do not block live critical notifications yet. - Update the Iris attention plan Phase B progress and rollback notes. Acceptance: - Attention decision ledger exists and can append/read decisions. - `should_notify` can be called in dry-run mode with representative candidates. - Tests cover tier classification, append-only behavior, and critical bypass classification. - No existing live notification behavior changes in this ticket. - Comment verification evidence and name the first emitters to integrate next. Expected check-in: after MC-5011 closes + 1 working session.